Set Theory Talks

Global set theory seminar and conference announcements

Wednesday seminar

Prague Set Theory Seminar
Dear all, The seminar meets on Wednesday September 27th at 11:00 in the Institute of Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building. Program: Ziemowit Kostana -- Separating big and small sticks "Stick" is a principle stating there exists a family F, consisting of ω_1 many countable subsets of ω_1, such that each uncountable subset of ω_1 contains a set from F. "Stick" trivially follows from CH, and is consistent with arbitrarily large continuum. A natural question connected with it, is whether we can assume (i.e. without obtaining a strictly stronger axiom) that the sets from F have a given large ordertype, say ω^ω. A claimed negative answer was given by William Chen in the paper Variations of the stick principle, European Journal of Mathematics, 3(3), 650-658. Although the proof is based on a correct (and to me pretty awesome) idea, it contains a substantial gap. I will elaborate on how, and to what extent, the proof can be fixed. Best, David

Wednesday seminar

Prague Set Theory Seminar
Dear all, The seminar meets on Wednesday September 20th at 11:00 in the Institute of Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building. Program: David Chodounsky -- Wadge classes on omega_1 I will introduce a game to compare complexity of constructions of objects of size omega_1. The original motivation was to compare constructions of Aronszajn trees, coherent sequences of functions, gaps in P(omega), and similar objects. I will prove some basic results on the resulting complexity classes. Joint work (in progress) with J. Bergfalk, O. Guzman, M. Hrusak. Best, David

This Week in Logic at CUNY

This Week in Logic at CUNY
This Week in Logic at CUNY:

- - - - Monday, Sep 18, 2023 - - - -

Rutgers Logic Seminar
Monday, Sept 18th, 3:30pm, Rutgers University, Hill 705
Alex Kruckman (Wesleyan)
The complexity of ages admitting a universal limit structure.

Abstract: An age is a hereditary class of finitely generated structures with the joint embedding property which is countable up to isomorphism. If K is an age, a K-limit is a countable structure M such that every finitely generated substructure of M is in K. A K-limit U is universal if every K-limit embeds in U. It is well-known that K has the amalgamation property (AP) if and only if K admits a homogeneous limit (the Fraïssé limit), which is universal. But not every age with a universal limit has AP. We show that, while the existence of a universal limit can be characterized by the well-definedness of a certain ordinal-valued rank on structures in K, it is not equivalent to any finitary diagrammatic property like AP. More precisely, we show that for ages in a fixed sufficiently rich language L, the property of admitting a universal limit is complete coanalytic. This is joint work with Aristotelis Panagiotopoulos.




Logic and Metaphysics Workshop
Date: Monday, Sept 18, 4.15-6.15pm (NY time)
Room: Philosophy Program Thesis Room (in 7113)
For meeting information, please sign up for our mailing list at https://logic.commons.gc.cuny.edu/about/
Will Nava (NYU)
Title: Non-classicality all the way up

Abstract: Nearly all non-classical logics that have been studied admit of classical reasoning about them. For example, in the logic K3, A or not-A is not a valid schema. However, ‘A or not-A’ is K3-valid or not K3-valid—this is, in some sense, a valid claim. In this talk, I introduce a simple framework for thinking about the logic of a given logic. This allows for a measure of the non-classicality of a logic—one on which almost all familiar non-classical logics are of the lowest grade of non-classicality. I’ll then discuss some strategies for generating and theorizing logics of higher grades of non-classicality, as well as some motivation for taking these logics seriously.




- - - - Tuesday, Sep 19, 2023 - - - -



- - - - Wednesday, Sep 20, 2023 - - - -



- - - - Thursday, Sep 21, 2023 - - - -

Infinite Games Workshop
Zoom Talk, details at https://jdh.hamkins.org/infinite-games-workshop/
Thursday 21 September, 11 am
Speaker: Davide Leonessi, The Graduate Center of the City University of New York
Title: Infinite draughts: a solved open game

Abstract: In this talk I will introduce open infinite games, and then define a natural generalization of draughts (checkers) to the infinite planar board. Infinite draughts is an open game, giving rise to the game value phenomenon and expressing it fully—the omega one of draughts is true $\omega_1$ and every possible defensive strategy of the losing player can be implemented.



- - - - Friday, Sep 22, 2023 - - - -

Model Theory Seminar
CUNY Graduate Center, Room 5383
Hybrid: Please email Victoria Gitman (vgitman@gmail.com) for meeting id.
Friday, Sept 22, 12:30-2:00pm
Michael Benedikt, University of Oxford
TBA




Logic Workshop
CUNY Graduate Center
Friday Sept 22, 2:00pm-3:30pm, Room 6417

David Marker, University of Illinois at Chicago
On equations of Poizat type

We look at differential equations of the form  where  is a rational function over the field of constants. We characterize when such equations are strongly minimal and study algebraic relations between solutions to two such equations.




Next Week in Logic at CUNY:

- - - - Monday, Sep 25, 2023 - - - -



- - - - Tuesday, Sep 26, 2023 - - - -



- - - - Wednesday, Sep 27, 2023 - - - -

The New York City Category Theory Seminar
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York
URL:  http://www.sci.brooklyn.cuny.edu/~noson/Seminar/index.html
Speaker:     Tomáš Gonda, University of Innsbruck.
Date and Time:     Wednesday September 27, 2023, 5:00 - 6:00 PM. ZOOM TALK. NOTE SPECIAL TIME!
Title:     A Framework for Universality in Physics, Computer Science, and Beyond.

Abstract: Turing machines and spin models share a notion of universality according to which some simulate all others. We set up a categorical framework for universality which includes as instances universal Turing machines, universal spin models, NP completeness, top of a preorder, denseness of a subset, and others. By identifying necessary conditions for universality, we show that universal spin models cannot be finite. We also characterize when universality can be distinguished from a trivial one and use it to show that universal Turing machines are non-trivial in this sense. We leverage a Fixed Point Theorem inspired by a result of Lawvere to establish that universality and negation give rise to unreachability (such as uncomputability). As such, this work sets the basis for a unified approach to universality and invites the study of further examples within the framework.





- - - - Thursday, Sep 28, 2023 - - - -



- - - - Friday, Sep 29, 2023 - - - -

Logic Workshop
CUNY Graduate Center
Friday Sept 29, 2:00pm-3:30pm, Room 6417
James Walsh, New York University


- - - - Other Logic News - - - -

CONFERENCE ANNOUNCEMENT
I am glad to announce the first installment of the meeting Groups Logic and Dynamics, on October 21. This will be a one day meeting held in New Brunswick. The format is modelled after the NERDS (https://nerds.math.uconn.edu/), for those of you who are familiar with it.

Please find the webpage containing all relevant information below. Registration is optional but strongly encouraged for planning purpose.

https://sites.math.rutgers.edu/~fc327/GLaDF2023/index.html

- Filippo Calderoni
fc327 (at) math.rutgers.edu


- - - - Web Site - - - -

Find us on the web at:  nylogic.github.io
(site designed, built & maintained by Victoria Gitman)

--------  ADMINISTRIVIA  --------

To subscribe/unsubscribe to this list, please email your request to jreitz@citytech.cuny.edu.

If you have a logic-related event that you would like included in future mailings, please email jreitz@citytech.cuny.edu.

Logic Seminar 19 Sept 2023 17:00 hrs at NUS by Neoh Tzeh Yuan

NUS Logic Seminar
Invitation to the Logic Seminar at the National University of Singapore Date: Tuesday, 19 September 2023, 17:00 hrs Place: NUS, Department of Mathematics, S17#04-06 Speaker: Neoh Tzeh Yuan Title: The complexity of 3-Occur-SAT. Abstract: The Boolean satisfiabilty problem (SAT) is a problem with great theoretical and practical interest. While heuristic algorithms tend to work well in practice, the widely believed strong exponential time hypothesis (SETH) conjectures that there is no deterministic algorithm for SAT in time O(c^n) for some constant c < 2. On the other hand, better bounds of O(c^n) with c < 2 have been found for various restricted (but still NP-complete) instances of SAT. One such problem is 3-Occur-SAT, where every variable in the formula occurs at most 3 times. Wahlstroem presented in 2005 an algorithm which solves the problem in time O(1.1279^n) and Peng and Xiao improved it (this year's IJCAI) to O(1.1238^n). I will present an algorithm that gives a further improvement to O(1.1199^n). I'll discuss the common bottleneck cases faced by previous efforts and introduce new reduction and branching rules that can circumvent these cases. The work I present is done in an internship at NUS / SOC supervised by Sanjay Jain and Frank Stephan from July to September 2023. URL: http://www.comp.nus.edu.sg/~fstephan/logicseminar.html

This Week in Logic at CUNY

This Week in Logic at CUNY
This Week in Logic at CUNY:

- - - - Monday, Sep 11, 2023 - - - -

Rutgers Logic Seminar
Monday, Sept 11th, 3:30pm, Rutgers University, Hill 705
Tom Benhamou, Rutgers
The Tukey order on ultrafilters, the Galvin property, and the Ultrapower Axiom



Logic and Metaphysics Workshop
Date: Monday, Sept 11, 4.15-6.15pm (NY time)
Room: Philosophy Program Thesis Room (in 7113)
For meeting information, please sign up for our mailing list at https://logic.commons.gc.cuny.edu/about/
Francesco Paoli, Cagliari
Title: Logical metainferentialism

Abstract: Logical inferentialism is the view that the meaning of the logical constants is determined by the rules of inference that govern their behaviour in proofs – in particular, sequent calculus proofs, according to the preferences of several recent authors. When it comes to the nuts and bolts, however, the view is tenable only if certain aspects – concerning e.g. harmony criteria for rules, normal forms, or proof-theoretic validity – are clarified. Sequent calculus inferentialists generally do so in terms of proofs from axioms, not of derivations from assumptions. Although the merits of this approach are already debatable in traditional settings, recent work on sequent calculi without Identity or Cut has revealed further shortcomings. Logical metainferentialism revises inferentialism in this more general perspective. In this talk, we will sketch the basics of this view and argue that, from this vantage point, the claim that LP is the “One True Logic” may appeal even to the inferentialistically inclined logician.


- - - - Tuesday, Sep 12, 2023 - - - -



- - - - Wednesday, Sep 13, 2023 - - - -



- - - - Thursday, Sep 14, 2023 - - - -



- - - - Friday, Sep 15, 2023 - - - -

NO CLASSES - Rosh Hashanah



Next Week in Logic at CUNY:

- - - - Monday, Sep 18, 2023 - - - -

Logic and Metaphysics Workshop
Date: Monday, Sept 18, 4.15-6.15pm (NY time)
Room: Philosophy Program Thesis Room (in 7113)
For meeting information, please sign up for our mailing list at https://logic.commons.gc.cuny.edu/about/
Will Nava (NYU)
Title: Non-classicality all the way up

Abstract: Nearly all non-classical logics that have been studied admit of classical reasoning about them. For example, in the logic K3, A or not-A is not a valid schema. However, ‘A or not-A’ is K3-valid or not K3-valid—this is, in some sense, a valid claim. In this talk, I introduce a simple framework for thinking about the logic of a given logic. This allows for a measure of the non-classicality of a logic—one on which almost all familiar non-classical logics are of the lowest grade of non-classicality. I’ll then discuss some strategies for generating and theorizing logics of higher grades of non-classicality, as well as some motivation for taking these logics seriously.




- - - - Tuesday, Sep 19, 2023 - - - -



- - - - Wednesday, Sep 20, 2023 - - - -



- - - - Thursday, Sep 21, 2023 - - - -



- - - - Friday, Sep 22, 2023 - - - -

Model Theory Seminar
CUNY Graduate Center, Room 5383
Hybrid: Please email Victoria Gitman (vgitman@gmail.com) for meeting id.
Friday, Sept 22, 12:30-2:00pm
Michael Benedikt, University of Oxford
TBA




Logic Workshop
CUNY Graduate Center
Friday Sept 22, 2:00pm-3:30pm, Room 6417

David Marker, University of Illinois at Chicago
On equations of Poizat type

We look at differential equations of the form  where  is a rational function over the field of constants. We characterize when such equations are strongly minimal and study algebraic relations between solutions to two such equations.





- - - - Other Logic News - - - -


- - - - Web Site - - - -

Find us on the web at:  nylogic.github.io
(site designed, built & maintained by Victoria Gitman)

--------  ADMINISTRIVIA  --------

To subscribe/unsubscribe to this list, please email your request to jreitz@citytech.cuny.edu.

If you have a logic-related event that you would like included in future mailings, please email jreitz@citytech.cuny.edu.

Wednesday seminar

Prague Set Theory Seminar
Dear all, The seminar meets on Wednesday September 13th at 11:00 in the Institute of Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building. Program: Jonathan Cancino Manriquez -- P-measures without P-points, part 2 We will finish the construction of a model with p-measures and no p-points. We also present an example, due to P. Borodulin-Nadzieja, of a p-measure whose construction does not rely on the existence of p-points in any way. Best, David

Logic Seminars next week

NUS Logic Seminar
Invitation to the Logic Seminar at the National University of Singapore FIRST TALK: Date: Tuesday, 12 September 2023, 17:00 hrs Place: NUS, Department of Mathematics, S17#04-06. Speaker: Borisa Kueljevic Title: L:ower bounds of sets of P-points Abstract: We will sketch the proof that MA(kappa) implies that each collection of P_c-points of size at most kappa which has a P_c-point as an RK upper bound also has a P_c-point as an RK lower bound. This is joint work with Dilip Raghavan and Jonathan Verner. SECOND TALK: Date: Thursday 14 September 2023, 17:00 hrs Place: Department of Mathematics, Room S17#04-06. Speaker: Jan Dobrowolski Title: Kim-independence in positive logic Abstract: The class of NSOP1 theories, originally introduced by Dzamonja and Shelah in 2004, has been studied very intensively in the last few years since the striking discovery of an independence relation called Kim-independence by Ramsey and Kaplan (based on earlier ideas of Kim and a work of Chernikov and Ramsey), which generalises forking independence in simple theories, and retains almost all its nice properties in the class of NSOP1 theories. I will start the talk with an overview of the notion of Kim-independence, and then I will present my joint work with Mark Kamsma on generalising Kim-independence to positive logic. In particular, I will discuss examples of positive NSOP1 theories falling into our framework such as the theory of existentially closed exponential fields (studied by Kirby and Haykazyan), the theory of fields with a generic submodule (studied by d'Elbee, Kaplan and Neuhauser) and the hyperimaginary extensions of NSOP1 theories. URL OF LOGIC SEMINAR: http://www.comp.nus.edu.sg/~fstephan/logicseminar.html

Logic Seminar Today

NUS Logic Seminar
Invitation to the Logic Seminar at the National University of Singapore Date: Tuesday, 5 September 2023, 17:00 hrs Place: NUS, Department of Mathematics, S17#04-06 Speaker: Sun Mengzhou Title: On the (non)elementarity of cofinal extension Abstract: Compared with end extensions, much little is known about cofinal extensions for models of fragments of PA. In particular, it is not even known known whether the elementarity of cofinal extensions can fail at some specific level. In this talk, I will try to give a complete answer. I will present a systemetic way to `compress' the truth of M into the second-order structure of a definable cut, and as a consequence, a correspondence theorem between the first-order theory of M and the second-order theory of the cut. Through this method I will construct several models with special cofinal extension properties. I will also show that every countable model of arithmetic fail to satisfy PA admits a non-elementary cofinal extension. It provides a model-theoretic characterization for PA in terms of cofinal extensions. URL: http://www.comp.nus.edu.sg/~fstephan/logicseminar.html

This Week in Logic at CUNY

This Week in Logic at CUNY
Welcome back, everyone!  Regular weekly mailings will continue through the start of winter break (late December).  Heads up - as usual, there are a number of three-day weekends in September, including the current Labor Day weekend.  Hope you are enjoying it.

Best,
Jonas Reitz



This Week in Logic at CUNY:

- - - - Monday, Sep 4, 2023 - - - -

COLLEGE CLOSED - Labor Day

- - - - Tuesday, Sep 5, 2023 - - - -



- - - - Wednesday, Sep 06, 2023 - - - -



- - - - Thursday, Sep 07, 2023 - - - -



- - - - Friday, Sep 08, 2023 - - - -

Logic Workshop
CUNY Graduate Center
Friday Sept 8, 2:00pm-3:30pm, Room 6417

Hans Schoutens, CUNY
The model-theory of compact spaces

A more correct title would read: the model-theory of the category of compact (Hausdorff) spaces. Last year, I gave a talk about the model-theory of categories, and this talk will be its continuation (but I will repeat everything that is relevant) in which I will look at one special case: COMP, the category of compact spaces. Let C be any model that is elementary equivalent to the category COMP (but if you’re a standard guy, you can just take C=COMP and everything is still interesting). The model C 'remembers' the topology of each of its objects (except we might have lost compactness). But it can recover much more, to an extent that I would almost call it 'foundational'. I will show how to reconstruct a model of PA, a model of the ORD (ordinals) and even a model of ZFC. If you wonder, which model of ZFC you get if you just start with COMP, the answer is: the same you woke up to this morning!



Next Week in Logic at CUNY:

- - - - Monday, Sep 11, 2023 - - - -

Logic and Metaphysics Workshop
Date: Monday, Sept 11, 4.15-6.15pm (NY time)
The room is yet to be determined. Meetings will be face to face only.
For meeting information, please sign up for our mailing list at https://logic.commons.gc.cuny.edu/about/
Francesco Paoli, Cagliari
Title: Logical metainferentialism

Abstract: Logical inferentialism is the view that the meaning of the logical constants is determined by the rules of inference that govern their behaviour in proofs – in particular, sequent calculus proofs, according to the preferences of several recent authors. When it comes to the nuts and bolts, however, the view is tenable only if certain aspects – concerning e.g. harmony criteria for rules, normal forms, or proof-theoretic validity – are clarified. Sequent calculus inferentialists generally do so in terms of proofs from axioms, not of derivations from assumptions. Although the merits of this approach are already debatable in traditional settings, recent work on sequent calculi without Identity or Cut has revealed further shortcomings. Logical metainferentialism revises inferentialism in this more general perspective. In this talk, we will sketch the basics of this view and argue that, from this vantage point, the claim that LP is the “One True Logic” may appeal even to the inferentialistically inclined logician.


- - - - Tuesday, Sep 12, 2023 - - - -



- - - - Wednesday, Sep 13, 2023 - - - -



- - - - Thursday, Sep 14, 2023 - - - -



- - - - Friday, Sep 15, 2023 - - - -

NO CLASSES - Rosh Hashanah




- - - - Other Logic News - - - -


- - - - Web Site - - - -

Find us on the web at:  nylogic.github.io
(site designed, built & maintained by Victoria Gitman)

--------  ADMINISTRIVIA  --------

To subscribe/unsubscribe to this list, please email your request to jreitz@citytech.cuny.edu.

If you have a logic-related event that you would like included in future mailings, please email jreitz@citytech.cuny.edu.

(KGRC) talks for the upcoming semester

Kurt Godel Research Center
The KGRC welcomes as guests: David Schrittesser visits the KGRC until September 14. Lou van den Dries visits the KGRC until September 15. Andreas Weiermann visits the KGRC on September 14 and gives a talk, see below. * * * Logic Colloquium Kurt Gödel Research Center Thursday, September 14 "Phase transitions for Gödel incompleteness" Andreas Weiermann (Ghent University, BE) In the first part we will survey several results regarding the provability/unprovability thresholds for natural assertions which are independent of the Peano axioms. In the second part we will present some recent findings regarding the phase transition for Friedman's version of the Bolzano Weierstrass theorem. These findings answer a question by Harvey M. Friedman. Time and Place Talk at 1:30pm in hybrid mode: on-site as well as via Zoom Universität Wien Institut für Mathematik Kolingasse 14-16 1090 Wien 1st floor Seminar room 10 Zoom: If you need the Zoom data and have not received the meeting link by the day before the talk, please contact richard.springer@univie.ac.at! For further information, please write to vera.fischer@univie.ac.at. * * * Set Theory Seminar Kurt Gödel Research Center Thursday, October 5 Thursday, October 12 Thursday, October 19 Thursday, November 9 Thursday, November 16 Thursday, November 23 Mini-course: "Convergence in Banach spaces of measures and cardinal characteristics of the continuum" Damian Sobota (KGRC) During this mini-course I will show how various properties of Banach spaces of measures (on compact spaces or Boolean algebras) are affected by values of the cardinal characteristics of the continuum occuring in Cichoń's diagram and van Douwen's diagram. We will in particular be interested in convergence properties of sequences of measures in weak* and weak topologies. Besides, we will study what impact extending the set-theoretic universe by forcing can have on topologies of ground model Banach spaces of measures. Finally, I will present connections between convergence of measures on compact spaces and filters on countable sets. Time and Place Talks at 11:30am in hybrid mode: on-site as well as via Zoom Universität Wien Institut für Mathematik Kolingasse 14-16 1090 Wien 1st floor Seminar room 10 Zoom: If you need the Zoom data and have not received the meeting link by the day before the respective talk, please contact richard.springer@univie.ac.at! For further information, please write to vera.fischer@univie.ac.at. * * * Set Theory Seminar Kurt Gödel Research Center Thursday, November 30 Thursday, December 7 Thursday, December 14 Thursday, January 11 Thursday, January 18 Thursday, January 25 Mini-course: "Forcing techniques for Cichoń's Maximum" Diego Alejandro Mejía (Shizuoka University, JP) Cichoń's diagram describes the connections between combinatorial notions related to measure, category, and compactness of sets of irrational numbers. In the second part of the 2010's decade, Goldstern, Kellner and Shelah constructed a forcing model of Cichoń's Maximum (meaning that all non-dependent cardinal characteristics are pairwise different) by using large cardinals. Some years later, we eliminated this large cardinal assumption. In this mini-course, we explore the forcing techniques to construct the Cichoń's Maximum model and much more. Concretely, we discuss the following components: 1. Tukey connections and cardinal characteristics of the continuum 2. Review of FS (finite support) iterations and basic methods to modify cardinal characteristics. 3. Preservation theory for cardinal characteristics. 4. FS iterations with measures and ultrafilters on the natural numbers. 5. Boolean Ultrapowers. 6. Forcing Intersected with submodels. Time and Place Talks at 11:30am in hybrid mode: on-site as well as via Zoom Universität Wien Institut für Mathematik Kolingasse 14-16 1090 Wien 1st floor Seminar room 10 Zoom: If you need the Zoom data and have not received the meeting link by the day before the respective talk, please contact richard.springer@univie.ac.at! For further information, please write to vera.fischer@univie.ac.at.

Wednesday seminar

Prague Set Theory Seminar
Dear all, The seminar meets on Wednesday September 6th at 11:00 in the Institute of Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building. Program: Jonathan Cancino Manriquez -- P-measures without P-points We will prove that consistently there are P-measures but no P-point exists. Best, David

Logic Seminar 5 Sept 2023 17:00 hrs at NUS by Sun Mengzhou

NUS Logic Seminar
Invitation to the Logic Seminar at the National University of Singapore Date: Tuesday, 5 September 2023, 17:00 hrs Place: NUS, Department of Mathematics, S17#04-06 Speaker: Sun Mengzhou Title: On the (non)elementarity of cofinal extension. Compared with end extensions, much little is known about cofinal extensions for models of fragments of PA. In particular, it is not even known known whether the elementarity of cofinal extensions can fail at some specific level. In this talk, I will try to give a complete answer. I will present a systemetic way to `compress' the truth of M into the second-order structure of a definable cut, and as a consequence, a correspondence theorem between the first-order theory of M and the second-order theory of the cut. Through this method I will construct several models with special cofinal extension properties. I will also show that every countable model of arithmetic fail to satisfy PA admits a non-elementary cofinal extension. It provides a model-theoretic characterization for PA in terms of cofinal extensions. URL: http://www.comp.nus.edu.sg/~fstephan/logicseminar.html

Logic Seminar 29 Aug 2023 17:00 hrs at NUS by Tran Chieu Minh

NUS Logic Seminar
Invitation to the Logic Seminar at the National University of Singapore Date: Tuesday, 29 August 2023, 17:00 hrs Place: NUS, Department of Mathematics, S17#04-06 Speaker: Tran Chieu Minh Title: Measure doubling of small sets in SO(3,R) Abstract: In a recent work, we show that if A is an open subset of SO(3,R) with sufficiently small normalized Haar measure, then mu(A^2) > 3.99 mu(A). This was conjectured by Emmanuel Breuillard and Ben Green around 15 years ago in the context of getting optimal bounds and finding continuous counterparts of product theorems by Helfgott, Pyber-Szabo, and Breuillard-Green-Tao. The result is also related to the Brunn-Minkowski inequalities from convex geometry, the Kunze-Stein phenomenon from harmonic analysis, and the Pillay conjectures from model theory. In this talk, I will explain these connections and discuss some ideas from the proof, which uses nonstandard analysis and neostable group theory. (The talk is based on joint work with Yifan Jing and Ruixiang Zhang) URL: http://www.comp.nus.edu.sg/~fstephan/logicseminar.html

Fwd: Aviles

Wrocław Set Theory Seminar


---------- Forwarded message ---------
Od: Grzegorz Plebanek <grzegorz.plebanek@math.uni.wroc.pl>
Date: czw., 24 sie 2023 o 20:39
Subject: Aviles
To: Piotr Borodulin-Nadzieja <pborod@math.uni.wroc.pl>, Szymon Żeberski <szymon.zeberski@pwr.edu.pl>, Paweł Krupski <pawel.krupski@pwr.edu.pl>, Robert Rałowski <robert.ralowski@pwr.edu.pl>, Maciej Korpalski <Maciej.Korpalski@math.uni.wroc.pl>, Arturo Antonio Martínez Celis Rodríguez <amartinezcelis@gmail.com>, <sebastian.jachimek@math.uni.wroc.pl>, Tomasz Żuchowski <tomasz.artur.zuchowski@gmail.com>


Panowie (Arturo: please use translator:-)
Antonio Aviles będzie  w IM UWR cały przyszły tydzień. 
Rysuje się idea  niezbyt formalnego seminarium we wtorek 29 sierpnia.
i jego odczyt (pod tytułem News from Murcia...)
Proponuje spotkać się na kawie w IM UWr o 16.00 i zacząć ok 16.20, a następnie udać się do pobliskiej restauracji (ok. 18.30). Wszystko trochę wcześniej niż zwykle- w IM trudniej wejść późnym wieczorem).
Dajcie mi e-mailem, proszę znać, kto będzie miał ochotę przyjść i, przede wszystkim,  kto wybierze się z nami na kolację (zapewne kuchnia azjatycka).
Szymonie, prześlij wiadomość. osobom, które pominąłem; nie mam wszystkich adresów.
Pozdrawiam, G

Wednesday seminar

Prague Set Theory Seminar
Dear all, There is no seminar next week (Wednesday August 30th). Instead, you may want to sneak in to the talk of Oleg Pikhurko -- Measurable Combinatorics which takes place on Wednesday at 9:00 at the Eurocomb conference at Mala Strana. https://iuuk.mff.cuni.cz/events/conferences/eurocomb23/program.html Mostly regular Wednesday seminars will resume in September. Best, David

Wednesday seminar

Prague Set Theory Seminar
Dear all, The seminar meets on Wednesday August 23rd at 11:00 in the Institute of Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building. Program: Chris Lambie-Hanson -- Ultracoherence We will present some results about the existence of nontrivial coherent families of functions, focusing especially on families indexed by ultrafilters. In the process, we will discuss some connections with forcing axioms, partition principles, and Čech-Stone compactifications of discrete spaces. Best, David

Wednesday seminar

Prague Set Theory Seminar
Dear all, Very likely there will be no Wednesday seminar the next and a couple of following weeks. I will send an announcement once we start meeting again (mid August--September). Also, in the meantime, let me know in case there would be a good reason for the seminar to meet -- an interesting guest visiting Prague, an interesting result you want to share,.. Best, David

Wednesday seminar

Prague Set Theory Seminar
Dear all, A quick update. This Wednesday July 12th we will have Pedro H. Zambrano giving a talk. https://sites.google.com/a/unal.edu.co/phzambranor/home I don't have the title/abstract of the talk yet, I will post it online once I get it. Here; https://calendar.math.cas.cz/seminar-on-reckoning-actual Also, we are moving to the air-conditioned room again. The seminar meets on Wednesday July 12th at 11:00 in the Institute of Mathematics CAS, Zitna 25, blue lecture hall, ground floor, rear building. Best, David On 09/07/2023 08:06, David Chodounsky wrote: > Dear all, > > The seminar meets on Wednesday July 12th at 11:00 in the Institute of > Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building. > > There is no fixed program yet. The plan is to do some ad hoc interesting > mathematics. > > > Best, > David

Wednesday seminar

Prague Set Theory Seminar
Dear all, The seminar meets on Wednesday July 12th at 11:00 in the Institute of Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building. There is no fixed program yet. The plan is to do some ad hoc interesting mathematics. Best, David

RIMS Set Theory Workshop: October 24-27, 2023

Conference
We are pleased to announce RIMS Set Theory Workshop 2023. This year's workshop will be held in a hybrid format of in-person at RIMS, Kyoto University, and online via Zoom. RIMS Set Theory Workshop 2023 - Large Cardinals and the Continuum - dates: Tue 24 Oct — Fri 27th Oct, 2023 venue: RIMS, Kyoto University, Japan & Online via Zoom organizer: Hiroshi Fujita (Ehime) contact: fujita.hiroshi.mh@ehime-u.ac.jp web page: https://tenasaku.com/RIMS2023/ We will have a mini-course by Joan Bagaria (Barcelona). Call for Contribution: We encourage both young researchers and experts to contribute with talks. Any topics in Set Theory and relevant areas are welcome. Both in-person talks at RIMS and online talks via Zoom are welcome. If you would like to give a talk at the workshop, please let us know by Fri 8 Sep, via Email to the organizer. Call for Participation: If you would like to participate in-person (at RIMS), please let us know by Fri 29 Sep, via Email to the organizer. If you would like to participate online (via Zoom), please let us know by Fri 15 Oct, via Email to the organizer. We are looking forward to your participation!
Link to more info

Wednesday seminar

Prague Set Theory Seminar
Dear all, The seminar meets on Wednesday June 28th at 11:00 in the Institute of Mathematics CAS, Zitna 25, blue lecture hall, ground floor, rear building. NOTE THE LOCATION CHANGE! Also let remind you the PhD defense of David Uhrik on Thursday afternoon next week (online only), and the restaurant visit (in person) which will follow. If you are interested in taking part, get in touch. Program: Jindrich Zapletal -- Fraisse limits and permutation models of ZF I introduce a new rich class of relational Fraisse structures. Their automorphism group admits detailed classification of its open subgroups, and their associated permutation model of ZF admits detailed study as well. Best, David

(KGRC) two talks on Thursday, June 29

Kurt Godel Research Center
The KGRC welcomes as guests: Clifton Ealy visits the KGRC until August 15. Thilo Weinert visits the KGRC until June 30. Serhii Bardyla visits the KGRC from June 24 to July 2. Yurii Khomskii visits the KGRC from June 27 to July 1. David Schrittesser visits the KGRC from June 30 to September 14. Aristotelis Panagiotopoulos visits the KGRC from July 10 to July 25. * * * Set Theory Seminar Kurt Gödel Research Center Thursday, June 29 "Spectra of combinatorial families" Lukas Schembecker (KGRC) I will give a brief overview of theory of the possible spectra of various combinatorial families such as mad families, independent families and other similar families. In particular I will detail the proof that there are no mad families of intermediate size in the Cohen model as an introduction to isomorphism-of-names arguments. Finally, I will sketch recent work of how to realise uncountable spectra of a_T, i.e. given an uncountable set C of cardinals (with some necessary extra assumptions) how to construct a model which has partitions of Baire space into compact sets of exactly the sizes prescribed in C. Time and Place Talk at 11:30am in hybrid mode: on-site as well as via Zoom Universität Wien Institut für Mathematik Kolingasse 14-16 1090 Wien 1st floor Seminar room 10 Zoom: If you need the Zoom data and have not received the meeting link by the day before the talk, please contact richard.springer@univie.ac.at! Please direct any other questions about this talk to vera.fischer@univie.ac.at. * * * Logic Colloquium Kurt Gödel Research Center Thursday, June 29 "Coloring universal pseudotrees" Monroe Eskew (KGRC) A pseudotree a set-theoretic tree without well-foundedness requirement; it is a partial order that is linear below any element. Assuming \kappa^{<\kappa} = \kappa, there is a definable pseudotree of size \kappa that contains a copy of every pseudotree of size \kappa. This pseudotree has the property that for every coloring of its nodes in finitely many colors, there is a monochromatic subtree isomorphic to the original one. We will sketch proofs of the above facts (which will be elementary and involve pictures) and discuss what we know about coloring pairs (where the situation is quite different). This is joint work with Thilo Weinert and David Chodounsky. Time and Place Talk at 3:00pm in hybrid mode: on-site as well as via Zoom Universität Wien Institut für Mathematik Oskar-Morgenstern-Platz 1 1090 Wien 2nd floor room HS 11 Zoom: If you need the Zoom data and have not received the meeting link by the day before the talk, please contact richard.springer@univie.ac.at! Please direct any other questions about this talk to vera.fischer@univie.ac.at.

Nankai Logic Colloquium

Nankai Logic Colloquium
Hello everyone,

The 2022-2023 school year is about to end. Yesterday we held the last Nankai Logic Colloquium for this semester. Thank you for attending!

Nankai Logic Colloquim is going to be resumed next semester. See you next semester!

P.S. Next semester there is going to be a major event in math logic held in Tianjin organized by Nankai University: the Asian Logic Conference! Follow this link for more details: https://logic.nankai.edu.cn/alc2023/main.htm

Best wishes,
Ming Xiao

(KGRC) two talks on Tuesday, June 20 and two talks on Thursday, June 22

Kurt Godel Research Center
The KGRC welcomes as guests: Clifton Ealy visits the KGRC until August 15. Thilo Weinert visits the KGRC until June 30. Jaroslav Supina visits the KGRC from June 18 to June 24. Serhii Bardyla visits the KGRC from June 24 to July 2. David Schrittesser visits the KGRC from June 30 to September 14. * * * Set Theory Seminar Kurt Gödel Research Center Tuesday, June 20 "Preservation results related to finitely additive measures on Boolean algebras" Diego Mejía (Shizuoka University, JP) Kamburelis (1989) proved that Boolean algebras with finitely additive measures preserve "strong witnesses" of the additivity of measure, which is one of the ingredients in the proof of Cichoń's maximum (forcing a constellation where all non-dependant entries in Cichoń's diagram are pairwise different). Based on Kamburelis' results, we present a generalization of the previous preservation result by taking away the "finitely additive measure" requirement. On the other hand, we give one example where a special property on the finitely additive measure gives the preservation of the additivity of the strong measure ideal, and also develop its corresponding preservation theory that doesn't rely on finitely additive measures. This strengthens preservation results by Judah and Shelah (1989). This is a joint work with Jörg Brendle and Miguel Cardona. Time and Place Talk at 3:00pm in hybrid mode: on-site as well as via Zoom Universität Wien Institut für Mathematik Kolingasse 14-16 1090 Wien 1st floor Seminar room 10 Zoom: If you need the Zoom data and have not received the meeting link by the day before the talk, please contact richard.springer@univie.ac.at! Please direct any other questions about this talk to vera.fischer@univie.ac.at. * * * Set Theory Seminar Kurt Gödel Research Center Tuesday, June 20 "Combinatorial Banach spaces" Sebastian Jachimek (University of Wrocław, PL) A combinatorial space is a Banach space induced by some family of subsets of natural numbers. During the talk I will present examples of such families and the appropriate Banach spaces. Furthermore, I will consider properties of those spaces, in particular in the context of containing isomorphic copies of the standard sequential Banach spaces $c_0$ and $\ell_1$. Time and Place Talk at 4:45pm in hybrid mode: on-site as well as via Zoom Universität Wien Institut für Mathematik Kolingasse 14-16 1090 Wien 2nd floor Seminar room 18 Zoom: If you need the Zoom data and have not received the meeting link by the day before the talk, please contact richard.springer@univie.ac.at! Please direct any other questions about this talk to vera.fischer@univie.ac.at. * * * Set Theory Seminar Kurt Gödel Research Center Thursday, June 22 "Katětov power ideals and the Fréchet-Urysohn property" Jaroslav Šupina (University of Košice, SK) At the beginning of the 1970s, M. Katětov discovered that iterated Fubini products of the Fréchet filter play a crucial role in the theory of Baire classes of functions. Recently, it has been shown that the transfinitely iterated Fréchet ideals are critical for maximal almost disjoint families or Ellentuck spaces. We show that these ideals fit well with the specific hierarchy of topological spaces related to delta-sets. Consequently, we get a solution to two problems on the Fréchet-Urysohn property of function spaces. This is a joint work with S. Bardyla and L. Zdomskyy. Time and Place Talk at 11:30am in hybrid mode: on-site as well as via Zoom Universität Wien Institut für Mathematik Kolingasse 14-16 1090 Wien 1st floor Seminar room 10 Zoom: If you need the Zoom data and have not received the meeting link by the day before the talk, please contact richard.springer@univie.ac.at! Please direct any other questions about this talk to vera.fischer@univie.ac.at. * * * Logic Colloquium Kurt Gödel Research Center Thursday, June 22 "Uniform Factoring for Operator Ideals" Kevin Beanland (Washington & Lee University, US) Beginning with the work of Jean Bourgain and later the Ph.D. thesis of Benoit Bossard, researchers have been using notions and methods of descriptive set theory to provide remarkable embedding results for classes of separable Banach spaces. More recently by considering a natural coding of the class of bounded linear operators between separable Banach spaces, many of these embedding results have been generalized to factorization results for operators; especially uniform factorization results for subsets of operator ideals. In this talk, I will explain this framework, outline some recent achievements in the area, and give avenues for future research. The work presented can be found in several papers written jointly with several coauthors including Ryan Causey, Dan Freeman, Bruno Braga, and Leandro Antunes. Time and Place Talk at 3:00pm in hybrid mode: on-site as well as via Zoom Universität Wien Institut für Mathematik Oskar-Morgenstern-Platz 1 1090 Wien 2nd floor room HS 11 Zoom: If you need the Zoom data and have not received the meeting link by the day before the talk, please contact richard.springer@univie.ac.at! Please direct any other questions about this talk to vera.fischer@univie.ac.at.

Wednesday seminar

Prague Set Theory Seminar
Dear all, The seminar meets on Wednesday June 21st at 11:00 in the Institute of Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building. On Wednesday June 28th we should have a seminar talk by Jindrich Zapletal, Wednesday July 5th is a state holiday -> no seminar. Seminars during July and August are TBD. David Uhrik will be defending his PhD thesis on Thursday June 29th. The defense is online only, starts at 15:30. https://is.cuni.cz/studium/eng/szz/index.php?do=detail&ffak=11320&ftyp=&kom=57302&term=778490 I assume after the defense we will go for a dinner/beer/coffee somewhere in the city center. Get in touch in case you are interested either in the defense Zoom link and/or in the event afterwards. Program (next week): Chris Lambie-Hanson -- Indecomposable ultrafilters and their utility The notion of "indecomposability" of an ultrafilter is a natural weakening of the notion of "completeness". Unlike countably complete nonprincipal ultrafilters, nontrivially indecomposable ultrafilters can consistently exist on relatively small cardinals (e.g., $\aleph_{\omega+1}$), yet indecomposable ultrafilters entail many of the same compactness principles as complete ultrafilters. In this talk, we will present some classical and some recent results on the existence of indecomposable ultrafilters and applications thereof. Depending on time and interest of the audience, these applications may involve tightness of topological spaces, partition relations, and compactness for chromatic numbers of graphs. The talk will include joint work with Jeffrey Bergfalk and Jing Zhang. Best, David

Conferencias del Seminario Colombo Mexicano de Teoría de Conjuntos 2023-I.

Seminario Colombo Mexicano de Teoría de Conjuntos
Seminario Colombo Mexicano de Teoría de Conjuntos

Cordial saludo a cada miembro del Grupo de Lógica de Bogotá.

Compartimos con ustedes un enlace de youtube donde podrán encontrar los videos de todas las sesiones del Seminario Colombo Mexicano de Teoría de Conjuntos que tuvimos durante el primer semestre del 2023. Allí también se encuentran los videos de las sesiones del año pasado.

Aprovechamos para agradecer a conferencistas y asistentes por la participación en el seminario durante este semestre, y los invitamos a continuar participando activamente en el seminario el próximo semestre.

Cordialmente:

Julián C. Cano (jc.canor@uniandes.edu.co). Universidad de los Andes, Bogotá.

Francisco S. Nieto (francisco.s.nieto@ciencias.unam.mx). Universidad Nacional Autónoma de México, Morelia.


Enlace de las conferencias:




 

(KGRC) TU Wien Mini Workshop and two KGRC talks

Kurt Godel Research Center
The KGRC welcomes as guests: Clifton Ealy (host: Matthias Aschenbrenner) visits the KGRC until August 15. Thilo Weinert (host: Vera Fischer) visits the KGRC until June 30. Ido Feldman (host: Miguel Moreno) visits the KGRC until June 17 and gives two talks, one at the TU Wien Mini Workshop and one at U Wien, details for both are below. Jindřich Zapletal (host: Vera Fischer) visits the KGRC from June 14 to June 16 and gives a talk, see below. Jaroslav Šupina (host: Vera Fischer) visits the KGRC from June 18 to June 24 and gives a talk, details to be announced at a later time. Serhii Bardyla (host: Vera Fischer) visits the KGRC from June 24 to July 2. David Schrittesser (host: Vera Fischer) visits the KGRC from June 30 to September 14. * * * We are happy to relay a message from Sandra Müller and Takehiko Gappo: TU Wien Mini Workshop in Set Theory on June 12 TU Wien Mini Workshop in Set Theory will take place on June 12 at Technical University of Vienna. There will be 6 talks given by the following speakers. - Lena Wallner (TU Wien) - William Chan (University of North Texas) - Ido Feldmann (Bar-Ilan University) - Adam Kwela (University of Gdańsk) - Dominik Adolf (Bar-Ilan University) - Bartosz Wcisło (University of Gdańsk) Given the limited seating capacity of the venue and arrangements for catering, we kindly request you to inform Takehiko Gappo (takehiko.gappo@tuwien.ac.at) in advance of your intention to attend. There is no registration fee. See the webpage for further information: https://sites.google.com/view/takehikogappo/conferences/tu-wien-mini-workshop We have decided to livestream the talks through Zoom! Please inform Takehiko Gappo if you would like to get the link. If you have any questions, please contact us at takehiko.gappo@tuwien.ac.at or sandra.mueller@tuwien.ac.at. Best regards, Takehiko Gappo and Sandra Müller * * * Set Theory Seminar Kurt Gödel Research Center Thursday, June 15 "Sums of triples in Abelian groups" Ido Feldman (Bar-Ilan University, IL) In 1974, Hindman proved that considering the semigroup $(\mathbb{N},+)$, for any partition $\mathbb{N} = S_0 \uplus S_1$, there exists an infinite $X \subseteq \mathbb{N}$ such that the set of its finite sums, is monochromatic, that is, contained in one of the cells. In contrast, in 2016 Komjáth showed that, for the group $(\mathbb{R}, +)$ there exists a partition $\mathbb{R} = S_0 \uplus S_1$ such that, whenever $X \subseteq \mathbb{R}$ is uncountable, not only is the set of finite sums not monochromatic, but already the set $\mathrm{FS}_2(X) := \{x + y | \{x, y\} \in [X]^2\}$ is not monochromatic. These results motivate a general investigation of additive Ramsey theory in the spirit of the classical partition calculus, and which in fact for some cases are a strengthening of the classical partition calculus. Motivated by similar problems at the level of $\aleph_2$, we extend Todorčević’s partition of three-dimension combinatorial cube to handle additional three dimensional objects. As a corollary we prove that the failure of continuum hypothesis asserts that for every Abelian group $G$ of size $\aleph_2$, there exist a coloring $c : G \to \mathbb{Z}$ such that, for every uncountable $X \subseteq G$ and every integer $k$, there exist three distinct elements $x, y, z \in X$ such that $c(x, y, z) = k$. This is a joint work with Assaf Rinot. For further reading the article is available here: https://londmathsoc.onlinelibrary.wiley.com/doi/10.1112/mtk.12200 Time and Place Talk at 11:30am in hybrid mode: on-site as well as via Zoom Universität Wien Institut für Mathematik Kolingasse 14-16 1090 Wien 1st floor Seminar room 10 Zoom: If you need the Zoom data and have not received the meeting link by the day before the talk, please contact richard.springer@univie.ac.at! Please direct any other questions about this talk to vera.fischer@univie.ac.at. * * * Logic Colloquium Kurt Gödel Research Center Thursday, June 15 "Group dynamics and models of ZF" Jindřich Zapletal (University of Florida, US) I will develop basics of the theory of permutation models of set theory with emphasis on the dialog between their internal features and dynamical properties of the underlying group action. There are many novel, clean theorems connecting fragments of the axiom of choice with group theory and dynamics. As an initial example, if the acting group is abelian, in the resulting permutation model every set is a union of a well-orderable collection of well-orderable sets. Time and Place Talk at 3:00pm in hybrid mode: on-site as well as via Zoom Universität Wien Institut für Mathematik Oskar-Morgenstern-Platz 1 1090 Wien 2nd floor room HS 11 Zoom: Zoom: If you need the Zoom data and have not received the meeting link by the day before the talk, please contact richard.springer@univie.ac.at! Please direct any other questions about this talk to vera.fischer@univie.ac.at.

Cross-Alps Logic Seminar (speaker: André Nies)

Cross-Alps Logic Seminar
On Friday 16.06.2023 at 16.00
André Nies (University of Auckland)
will give a talk on 
Computably totally disconnected, locally compact groups

Please refer to the usual webpage of our LogicGroup for more details and the abstract of the talk.
The seminar will be held remotely through Webex. Please write to vincenzo.dimonte [at] uniud [dot] it for the link to the event.

The Cross-Alps Logic Seminar is co-organized by the logic groups of Genoa, Lausanne, Turin and Udine as part of our collaboration in the project PRIN 2017 'Mathematical logic: models, sets, computability'.

All the best,
Vincenzo

Set Theory and Topology Seminar 13.06.2023 Paweł Krupski

Wrocław Set Theory Seminar
I am happy to announce that at the seminar in Set Theory and Topology (on Tuesday 06.06.2023 at 17:15 in room A.4.1 C-19  (Wrocław University of Science and Technology) the lecture:
"Remarks and questions on hyperspaces of knots: Borel complexity and local contractibility"
will be presented by

Paweł Krupski


Feel free to spread this information among Your colleagues.

I'm looking forward to seeing You
Szymon Żeberski

(on behalf of the organizers, i.e. Piotr Borodulin-Nadzieja, Paweł Krupski, Aleksandra Kwiatkowska, Grzegorz Plebanek, Robert Rałowski  and myself)


About 15 minutes before the seminar we invite you for coffee and a chat to social room A.4.1.A in C-19. 

After the (last in this semester) seminar, we plan to continue informally at Liquid Form :)

*****************************************************************************************************************

Our webpages:
https://settheory.pwr.edu.pl/
http://www.math.uni.wroc.pl/seminarium/topologia

Nankai Logic Colloquium

Nankai Logic Colloquium

Hello everyone,

This week our weekly Nankai Logic Colloquium is going to be in the morning.

Our speaker this week will be Shaun Allison from the University of Toronto. This talk is going to take place this Friday,  June 9th,  from 9am to 10am(UTC+8, Beijing time). 

Title: Countable treeable Borel equivalence relations are classifiable by $\ell_1$.

Abstract: A celebrated result of Gao-Jackson is that every equivalence relation induced by a Borel action of a countable abelian group is hyperfinite. Greg Hjorth asked if indeed every countable Borel equivalence relation that is Borel-reducible to an orbit equivalence relation induced by an abelian Polish group is hyperfinite. We prove that while the answer to Hjorth's question is "yes" in many situations, in fact every countable treeable Borel equivalence relation is classifiable by an abelian Polish group. Given that the free part of the Bernoulli shift action of F_2 is treeable but not hyperfinite, this answers Hjorth's question in the negative in general. The proof relies on a subtle property of a treeing which we call "stretched", as well as a free Banach space construction. We will spend much of the time explaining the context and all of the relevant definitions behind this result, and then we will give a sketch of the proof. We end with some suggestions for future directions.


__________________________________________________________________________________________________

Title :The 32nd Nankai Logic Colloquium --Shaun Allison

Time :9:00am, Jun. 9, 2023(Beijing Time)

Zoom Number :893 1745 8343

Passcode : 283146

Link :https://us02web.zoom.us/j/89317458343?pwd=L01Hc28yc0J2OGk3c3VPS3gvVjVndz09

_____________________________________________________________________


Best wishes,

Ming Xiao





Cross-Alps Logic Seminar (speaker: Ulrich Kohlenbach)

Cross-Alps Logic Seminar
On Friday 09.06.2023 at 16.00
Ulrich Kohlenbach (Technische Universität Darmstadt)
will give a talk on 
Proof mining: Recent developments

Please refer to the usual webpage of our LogicGroup for more details and the abstract of the talk.
The seminar will be held remotely through Webex. Please write to vincenzo.dimonte [at] uniud [dot] it for the link to the event.

The Cross-Alps Logic Seminar is co-organized by the logic groups of Genoa, Lausanne, Turin and Udine as part of our collaboration in the project PRIN 2017 'Mathematical logic: models, sets, computability'.

All the best,
Vincenzo

Nankai Logic Colloquium

Nankai Logic Colloquium

Hello everyone,

This week our weekly Nankai Logic Colloquium is going to be in the afternoon.

Our speaker this week will be Dominik Kwietniak from Jagiellonian University. This talk is going to take place this Friday,  June 2nd,  from 4pm to 5pm(UTC+8, Beijing time). 

Title: An anti-classification theorem for the topological conjugacy
problem for Cantor minimal systems

Abstract:
The isomorphism problem in dynamics  dates back to a question of von
Neumann from 1932: Is it possible to classify (in some reasonable
sense) the ergodic measure-preserving diffeomorphisms of a compact
manifold up to isomorphism? We would like to study a similar problem:
let C be the Cantor set and let Min(C) stand for the space of all
minimal homeomorphisms of the Cantor set. Recall that a Cantor set
homeomorphism T is in Min(C) if every orbit of T is dense in C.  We
say that S and T in Min(C) are topologically conjugate if there exists
a Cantor set homeomorphism h such that Sh=hT. We prove an
anti-classification result showing that even for very liberal
interpretations of what a "reasonable'' classification scheme might
be, a classification of minimal Cantor set homeomorphism up to
topological conjugacy is impossible. We see is as a consequence of the
following: we prove that the topological conjugacy relation of Cantor
minimal systems TopConj treated as a subset of Min(C) x Min(C) is
complete analytic. In particular, TopConj is a non-Borel subset of
Min(C) x Min(C). Roughly speaking, it means that it is impossible to
tell if two minimal Cantor set homeomorphisms are topologically
conjugate  using only a countable amount of information and
computation.

Our result is proved by applying a Foreman-Rudolph-Weiss-type
construction used for an anti-classification theorem for ergodic
automorphisms of the Lebesgue space. We find a continuous map F from
the space of all subtrees over non-negative integers N with
arbitrarily long branches into the class of minimal homeomorphisms of
the Cantor set. Furthermore, F is a reduction, which means that a tree
T is ill-founded if and only if F(T) is topologically conjugate to its
inverse. Since the set of ill-founded trees with arbitrarily long
branches is a well-known example of a complete analytic set, we see
that it is essentially impossible to classify which minimal Cantor set
homeomorphisms are topologically conjugate to their inverses.

This is joint work with Konrad Deka, Felipe García-Ramos, Kosma
Kapsrzak, Philipp Kunde (all from the Jagiellonian University in
Kraków).

__________________________________________________________________________________________________

Title :The 31st Nankai Logic Colloquium --Dominik Kwietniak

Time :16:00pm, Jun. 2, 2023(Beijing Time)

Zoom Number : 876 3579 6414

Passcode : 318535

Link :https://us02web.zoom.us/j/87635796414?pwd=M1hZSEFvL0FzMUZQcHVCQ0w2QlhtUT09

_____________________________________________________________________


Best wishes,

Ming Xiao





Set Theory and Topology Seminar 6.06.2023 Piotr Szewczak (UKSW)

Wrocław Set Theory Seminar
I am happy to announce that at the seminar in Set Theory and Topology (on Tuesday 06.06.2023 at 17:15 in room A.4.1 C-19  (Wrocław University of Science and Technology) the lecture:
"Totally imperfect Menger sets"
will be presented by

Piotr Szewczak (UKSW)


Feel free to spread this information among Your colleagues.

I'm looking forward to seeing You
Szymon Żeberski

(on behalf of the organizers, i.e. Piotr Borodulin-Nadzieja, Paweł Krupski, Aleksandra Kwiatkowska, Grzegorz Plebanek, Robert Rałowski  and myself)


Abstract

A set of reals X is Menger if for any countable sequence of open covers of X one can pick finitely many elements from every cover in the sequence such that the chosen sets cover X. Any set of reals of cardinality smaller than the dominating number d is Menger and there is a non-Menger set of cardinality d. By the result of Bartoszyński and Tsaban, in ZFC, there is a totally imperfect (with no copy of the Cantor set inside) Menger set of cardinality d. We solve a problem, whether there is such a set of cardinality continuum. Using an iterated Sacks forcing and topological games we prove that it is consistent with ZFC that d<c and each totally imperfect Meneger set has cardinality less or equal than d.
This is a joint work with Valentin Haberl and Lyubomyr Zdomskyy.
The research was funded by the National Science Centre, Poland  and the Austrian Science Found under the Weave-UNISONO call in the Weave programme, project: Set-theoretic aspects of topological selections 2021/03/Y/ST1/00122.


About 15 minutes before the seminar we invite you for coffee and a chat to social room A.4.1.A in C-19. 


*****************************************************************************************************************

Our webpages:
https://settheory.pwr.edu.pl/
http://www.math.uni.wroc.pl/seminarium/topologia

Nankai Logic Colloquium

Nankai Logic Colloquium

Hello everyone,

This week our weekly Nankai Logic Colloquium is going to be in the afternoon.

Our speaker this week will be Liuzhen Wu from the Academy of Mathematical and Systems Sciences, CAS. This talk is going to take place this Friday,  May 26th,  from 4pm to 5pm(UTC+8, Beijing time). 


title: Definability of the nonstationary ideal on $\omega_1$

abstract: The nonstationary ideals are natural nontrivial ideals defined on all uncountable regular cardinals. In this talk, various aspects of definability of nonstationary ideals on uncountable cardinals are explored. The main focus is  the definability of nonstationary ideal on $\omega_1$ ($NS_{\omega_1}$ for short) in some canonical models of set theory. In particular, under MM or (*) axiom, $NS_{\omega_1}$ is not $\Pi_1$ definable. On the other hand, it is consistent that in some model of $PFA$, $NS_{\omega_1}$ is $\Pi_1$ definable. This is based on the accumulated work of Aspero, Hoffelner, Larson, Schindler, Sun, Wu.

__________________________________________________________________________________________________

Title : The 30th Nankai Logic Colloquium --Liuzhen Wu

Time :16:00pm, May. 26, 2023 (Beijing Time) 

Zoom Number : 851 5601 8255

Passcode : 136440

Link :https://us02web.zoom.us/j/85156018255?pwd=UjFUb3cwT0poY0JYakRub2kyNGdSdz09

_____________________________________________________________________


Best wishes,

Ming Xiao





Set Theory and Topology Seminar 30.05.2023 Zbigniew Lipecki

Wrocław Set Theory Seminar
I am happy to announce that at the seminar in Set Theory and Topology (on Tuesday 30.05.2023 at 17:15 in room A.4.1 C-19  (Wrocław University of Science and Technology) the lecture:
"How noncompact is the space of Lebesgue measurable functions?"
will be presented by

Zbigniew Lipecki (IM PAN)


Feel free to spread this information among Your colleagues.

I'm looking forward to seeing You
Szymon Żeberski

(on behalf of the organizers, i.e. Piotr Borodulin-Nadzieja, Paweł Krupski, Aleksandra Kwiatkowska, Grzegorz Plebanek, Robert Rałowski  and myself)


Abstract

The space in question is the space $\textfrak M$ of Lebesgue measurable subsets of the unit interval equipped with the usual Fr'echet--Nikodym (semi)metric. We show that there exists a sequence of elements of $\textfrak M$ such that their mutual distances are > 1/2. It seems to be an open problem whether "1/2" can be replaced here by a bigger constant C. We show that C must be smaller than 9/14. Moreover, we present a version of the problem in terms of binary codes.


About 15 minutes before the seminar we invite you for coffee and a chat to social room A.4.1.A in C-19. 


*****************************************************************************************************************

Our webpages:
https://settheory.pwr.edu.pl/
http://www.math.uni.wroc.pl/seminarium/topologia

Charla de Justin Moore en el Seminario Colombo Mexicano de Teoría de Conjuntos

Seminario Colombo Mexicano de Teoría de Conjuntos

Seminario Colombo Mexicano de Teoría de Conjuntos

 

May 25

4:00 p.m. - 5:00 p.m. (Colombia time)  


Large minimal non-$\sigma$-scattered orders
Justin T. Moore
Cornell University

Abstract. We present new constructions of linear orders which are minimal with respect to being non-$\sigma$-scattered. Specifically, we will show that Jensen's diamond principle implies that there is a minimal Countryman line, answering a question of Baumgartner. We will also construct the first consistent examples of minimal non-$\sigma$-scattered linear order of cardinality greater than $\aleph_1$. In fact, this can be achieved at any successor cardinal $\kappa^+$, both via forcing constructions and via axiomatic principles which hold in Gödel's Constructible Universe. These linear order of cardinality $\kappa^+$ have the property that their square is the union of $\kappa$-many chains. 
This is joint work with James Cummings and Todd Eisworth.

Zoom meeting information.

Meeting ID: 856 1882 0721

Passcode: 123456

https://cuaieed-unam.zoom.us/j/85618820721


This Week in Logic at CUNY

This Week in Logic at CUNY
Hi everyone,

This will be the final edition of "This Week in Logic" for the Spring 2023 semester.  Regular mailings will resume in late August.  We will send out special editions for events over the summer - please send me your notifications.

Be well,
Jonas


This Week in Logic at CUNY:

- - - - Monday, May 22, 2023 - - - -



- - - - Tuesday, May 23, 2023 - - - -

MAMLS Spring Fling at Rutgers University
The MAMLS Spring Fling meeting will take place May 23-26 at Rutgers University, New Brunswick, New Jersey. More information about the meeting can be found on its website (https://sites.math.rutgers.edu/~fc327/MAMLS2023/index.html). Registration is free and everyone who plans to attend is encouraged to register for logistics purposes.


- - - - Wednesday, May 24, 2023 - - - -



- - - - Thursday, May 25, 2023 - - - -



- - - - Friday, May 26, 2023 - - - -





- - - - Other Logic News - - - -


- - - - Web Site - - - -

Find us on the web at:  nylogic.github.io
(site designed, built & maintained by Victoria Gitman)

--------  ADMINISTRIVIA  --------

To subscribe/unsubscribe to this list, please email your request to jreitz@citytech.cuny.edu.

If you have a logic-related event that you would like included in future mailings, please email jreitz@citytech.cuny.edu.

(KGRC) four talks, long and short

Kurt Godel Research Center
The KGRC welcomes as guests: Clifton Ealy (host: Matthias Aschenbrenner) visits the KGRC until August 15. Thilo Weinert (host: Vera Fischer) visits the KGRC from May 10 to June 30. Sergei Starchenko (host: Matthias Aschenbrenner) visits the KGRC from May 13 to May 27 and gives a talk, see below. Aaron Anderson (host: Matthias Aschenbrenner) visits the KGRC from May 23 to May 24 and gives a talk, see below. Fabian Kaak (host: Vera Fischer) visits the KGRC from May 23 to May 26 and gives a short talk, see below. Nigel Pynn-Coates (host: Matthias Aschenbrenner) visits the KGRC from June 2 to June 10. Ido Feldman (host: Miguel Moreno) visits the KGRC from June 11 to June 17 and gives a talk, details to be announced at a later time. Jaroslav Šupina (host: Vera Fischer) visits the KGRC from June 18 to June 24 and gives a talk, details to be announced at a later time. David Schrittesser (host: Vera Fischer) visits the KGRC from June 30 to September 14. * * * Model Theory Seminar Kurt Gödel Research Center Wednesday, May 24 "Distality in Continuous Logic" Aaron Anderson (University of California, LA, US) We examine distal theories and structures in the context of continuous logic, providing several equivalent definitions. By studying the combinatorics of fuzzy VC-classes, we find continuous versions of (strong) honest definitions and distal cell decompositions. By studying generically stable Keisler measures in continuous logic, we apply the theory of continuous distality to analytic versions of graph regularity. Time and Place Talk at 3:00pm Universität Wien Institut für Mathematik Kolingasse 14-16 1090 Wien 1st floor Seminar room 10 Please direct any questions about this talk to matthias.aschenbrenner@univie.ac.at. * * * Set Theory Seminar Kurt Gödel Research Center Thursday, May 25 This installment of the seminar will see two shorter talks: "Set theory of a Suslin line" Fabian Kaak (Universität Kiel, DE) A Suslin line is a linear ordering, which is in some way quite similar to the real line. We will discuss in what ways the set theory of the real line can be adapted to a Suslin line. We give a characterization of Borel sets of the Suslin line, look at a few cardinal characteristics and play games on a Suslin tree. ... as well as ... "Strong Measure Zero Sets on the Higher Cantor Space" Nick Chapman (TU Wien) As introduced by Borel in the early 20th century, a set of reals is strong measure zero if it can be covered by a sequence of intervals whose lengths shrink arbitrarily fast. This notion admits a natural generalisation in the context of the higher Cantor space $2^\kappa$. However, contrasting the situation on $2^\omega$, much about the behaviour of strong measure zero sets on $2^\kappa$ is unknown; in particular, the consistency of Borel's Conjecture in this context ("A set is strong measure zero iff it has size at most $\kappa$") is still open. We shall discuss a statement closely related to the Borel Conjecture: for $\kappa$ inaccessible we will sketch the construction of a model of $|2^\kappa| = \kappa^{++}$ and "$\forall X \subseteq 2^\kappa: X \text{ is strong measure zero iff } |X| \leq \kappa^+$", focusing on some of the difficulties one runs into when generalising proof strategies from the countable case. Time permitting, we will also briefly touch on Halko's notion of stationary strong measure zero sets. The content of this talk is extracted from my Master thesis and is based on earlier work by Johannes Schürz. Time and Place Both talks, one after the other, first talk at 11:30am, in hybrid mode: on-site as well as via Zoom Universität Wien Institut für Mathematik Kolingasse 14-16 1090 Wien 1st floor Seminar room 10 Zoom: If you need the Zoom data and have not received the meeting link by the day before the talk, please contact richard.springer@univie.ac.at! Please direct any other questions about these two talks to vera.fischer@univie.ac.at. * * * Logic Colloquium Kurt Gödel Research Center Thursday, May 25 "On Hausdorff limits of images of o-minimal families in real tori" Sergei Starchenko (University of Notre Dame, US) Let $\{ X_s \colon x\in S \}$ be a family of subsets of ${\mathbb R}^n$ definable in some o-minimal expansion of the real field. Let $\Gamma \subseteq {\mathbb R}^n$ be a lattice and $\pi \colon {\mathbb R}^n/\Gamma \to \mathbb T$ be the quotient map. In a series of papers (published and unpublished) together with Y.Peterzil we considered Hausdorff limits of the family $\{ \pi(X_s) \colon s\in S\}$ and provided their description. In this talk I describe model theoretic tools used in the description. Talk at 3:00pm in hybrid mode: on-site as well as via Zoom Universität Wien Institut für Mathematik Oskar-Morgenstern-Platz 1 1090 Wien 2nd floor room HS 11 Zoom: If you need the Zoom data and have not received the meeting link by the day before the talk, please contact richard.springer@univie.ac.at! Please direct any other questions about this talk to vera.fischer@univie.ac.at.

Set Theory and Topology Seminar 23.05.2023 Barnabas Farkas

Wrocław Set Theory Seminar
I am happy to announce that at the seminar in Set Theory and Topology (on Tuesday 23.04.2023 at 17:15 in room A.4.1 C-19  (Wrocław University of Science and Technology) the lecture:
"A tool to avoid some technical forcing arguments when working with the Hechler forcing"
will be presented by

Barnabas Farkas (TU Wien)


Feel free to spread this information among Your colleagues.

I'm looking forward to seeing You
Szymon Żeberski

(on behalf of the organizers, i.e. Piotr Borodulin-Nadzieja, Paweł Krupski, Aleksandra Kwiatkowska, Grzegorz Plebanek, Robert Rałowski  and myself)


Abstract

I'm going to present that virtually every result saying that finite support iterations of the Hechler forcing preserve a cardinal invariant being small and its dual being large can be reduced to a single preservation theorem. In other words, this theorem eliminates the technical forcing arguments from the proofs of these results and reduces them to easy coding exercises. 

About 15 minutes before the seminar we invite you for coffee and a chat to social room A.4.1.A in C-19. 


*****************************************************************************************************************

Our webpages:
https://settheory.pwr.edu.pl/
http://www.math.uni.wroc.pl/seminarium/topologia

Charla de Alfredo Zaragoza en el Seminario Colombo Mexicano de Teoría de Conjuntos

Seminario Colombo Mexicano de Teoría de Conjuntos

Seminario Colombo Mexicano de Teoría de Conjuntos

 

Mayo 18

4:00 p.m. - 5:00 p.m. (hora de Colombia)  

 

Algunos ejemplos de espacios topológicos tales que dim(X) = dim(K(X)) = 1 

Alfredo Zaragoza
Universidad Michoacana de San Nicolás de Hidalgo

Resumen. En general, si tenemos un espacio topológico X de dimensión uno, la dimensión de su hiperespacio de subconjuntos compactos K(X) con la topología de Vietoris no es finita. En esta plática presentamos varios ejemplos de espacios topológicos X de dimensión uno tales que la dimensión de su hiperespacio K(X) también es uno.

 

Zoom meeting information.

Meeting ID: 856 1882 0721

Passcode: 123456

https://cuaieed-unam.zoom.us/j/85618820721


Cross-Alps Logic Seminar (speaker: Jacques Duparc)

Cross-Alps Logic Seminar
On Friday 19.05.2023 at 16.00
Jacques Duparc (Université de Lausanne)
will give a talk on 
The Wadge order on the Cantor Space and on the Scott Domain

Please refer to the usual webpage of our LogicGroup for more details and the abstract of the talk.
The seminar will be held remotely through Webex. Please write to vincenzo.dimonte [at] uniud [dot] it for the link to the event.

The Cross-Alps Logic Seminar is co-organized by the logic groups of Genoa, Lausanne, Turin and Udine as part of our collaboration in the project PRIN 2017 'Mathematical logic: models, sets, computability'.

All the best,
Vincenzo

Nankai Logic Colloquium

Nankai Logic Colloquium

Hello everyone,

This week our weekly Nankai Logic Colloquium is going to be in the afternoon.

Our speaker this week will be Guozhen Shen from Wuhan University. This talk is going to take place this Friday,  May 19th,  from 4pm to 5pm(UTC+8, Beijing time). 

Title: A surjection from square onto power


Abstract: In 1892, Cantor proved that, for all sets $A$, there are no bijections between $A$ and the power set of $A$. Cantor's construction is so explicit that it can be carried out in ZF (the Zermelo--Fraenkel set theory without the axiom of choice). In 1906, by virtue of Zermelo's well-ordering theorem, Hessenberg proved the idempotency theorem, which states that there is a bijection between $A$ and the square of $A$ for all infinite sets $A$. (Another proof of the idempotency theorem was given by Zorn in 1944 using Zorn's lemma.) In 1924, Tarski proved that the idempotency theorem is in fact equivalent to the axiom of choice. On the other hand, in 1954, Specker proved in ZF a surprising generalization of Cantor's theorem, which states that, for all infinite sets $A$, there are no injections from the power set of $A$ into the square of $A$. It is then natural to ask whether it is provable in ZF that, for all infinite sets $A$, there are no surjections from the square of $A$ onto the power set of $A$. This question is known as the dual Specker problem and was proposed by Truss in 1973. In this talk, we give a negative answer to this question; that is, the existence of an infinite set $A$ such that the square of $A$ maps onto the power set of $A$ is consistent with ZF. This is joint work with Yinhe Peng and Liuzhen Wu.

__________________________________________________________________________________________________

Title The 29th Nankai Logic Colloquium --Guozhen Shen

Time 16:00pm, May. 19, 2023 (Beijing Time) 

Zoom Number 856 2849 0880

Passcode  073635

Link https://us02web.zoom.us/j/85628490880?pwd=dTBrV0NLc0l1bmFTY1RHR0d0TUNDZz09

_____________________________________________________________________


Best wishes,

Ming Xiao





This Week in Logic at CUNY

This Week in Logic at CUNY
This Week in Logic at CUNY:

- - - - Monday, May 15, 2023 - - - -

Logic and Metaphysics Workshop
Date: Monday, May 15, 4.15-6.15pm (NY time), GC 9206
NOTE: Meetings this semester are in person only (no zoom)
For meeting information, please sign up for our mailing list at https://logic.commons.gc.cuny.edu/about/

Maciej Sendłak (Warsaw).
Title: Explanatory realism and counterfactuals

Abstract: In my talk, I want to propose a novel approach to the question of counterfactuals. This is grounded in two assumptions, imported from the philosophy of science. The first one has it that to explain a phenomenon is to show how it depends on something else. The second states that the correct explanation ought to be contrastive. This means that a good explanation justifies the occurrence of a phenomenon and – at the same time – excludes occurrence of some other states of affairs. I am going to argue that – together with the assumption that conditionals express a dependence relation between A and C – the above gives ground for analysis of counterfactuals. According to this proposal: “A>C” is true at the world of evaluation iff there is a relation of dependence that hold between referents of A and C, and the same relation of dependence holds in the world of evaluation.





- - - - Tuesday, May 16, 2023 - - - -



- - - - Wednesday, May 17, 2023 - - - -

The New York City Category Theory Seminar
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York

Speaker:     Arthur Parzygnat, Nagoya University.

Date and Time:     Wednesday May 17, 2023, 7:00 - 8:30 PM. IN PERSON TALK.

Title:     Inferring the past and using category theory to define retrodiction.


Abstract: Classical retrodiction is the act of inferring the past based on knowledge of the present. The primary example is given by Bayes' rule P(y|x) P(x) = P(x|y) P(y), where we use prior information, conditional probabilities, and new evidence to update our belief of the state of some system. The question of how to extend this idea to quantum systems has been debated for many years. In this talk, I will lay down precise axioms for (classical and quantum) retrodiction using category theory. Among a variety of proposals for quantum retrodiction used in settings such as thermodynamics and the black hole information paradox, only one satisfies these categorical axioms. Towards the end of my talk, I will state what I believe is the main open question for retrodiction, formalized precisely for the first time. This work is based on the preprint https://arxiv.org/abs/2210.13531 and is joint work with Francesco Buscemi.





- - - - Thursday, May 18, 2023 - - - -



- - - - Friday, May 19, 2023 - - - -

Set Theory Seminar
CUNY Graduate Center
Friday, May 19, 12:30pm NY time
Virtual: Please email Victoria Gitman (vgitman@gmail.com) for meeting id.

Miha Habič, Bard College at Simon's Rock
Some old and new results on nonamalgamable forcing extensions

Fixing some countable transitive model  of set theory, we can consider its generic multiverse, the family of all models obtainable from  by taking any sequence of forcing extensions and ground models. There is an attractive similarity between the generic multiverse and the Turing degrees, but the multiverse has the drawback (or feature?) that it contains nonamalgamable models, that is, models with no common upper bound, as was observed by several people, going back to at least Mostowski. In joint work with Hamkins, Klausner, Verner, and Williams in 2019, we studied the order-theoretic properties of the generic multiverse and, among other results, gave a characterization of which partial orders embed nicely into the multiverse. I will present our results in the simplest case of Cohen forcing, as well as existing generalizations to wide forcing, and some new results on non-Cohen ccc forcings.




Next Week in Logic at CUNY:

- - - - Monday, May 22, 2023 - - - -



- - - - Tuesday, May 23, 2023 - - - -

MAMLS Spring Fling at Rutgers University
The MAMLS Spring Fling meeting will take place May 23-26 at Rutgers University, New Brunswick, New Jersey. More information about the meeting can be found on its website (https://sites.math.rutgers.edu/~fc327/MAMLS2023/index.html). Registration is free and everyone who plans to attend is encouraged to register for logistics purposes.


- - - - Wednesday, May 24, 2023 - - - -



- - - - Thursday, May 25, 2023 - - - -



- - - - Friday, May 26, 2023 - - - -





- - - - Other Logic News - - - -


- - - - Web Site - - - -

Find us on the web at:  nylogic.github.io
(site designed, built & maintained by Victoria Gitman)

--------  ADMINISTRIVIA  --------

To subscribe/unsubscribe to this list, please email your request to jreitz@citytech.cuny.edu.

If you have a logic-related event that you would like included in future mailings, please email jreitz@citytech.cuny.edu.

Applications of Set Theory, Lodz, Poland, September 4-8 2023

Conference
Dear All, We would like to inform you about the session "Applications of Set Theory" which will be held as a part of Spanish-Polish Mathematical Meeting in Lodz, Poland, 4-8 Sep 2023. The following people kindly agreed to speak at the session: * Alberto Salguero Alarcón (Badajoz) * David Aspero (Norwich) * Antonio Aviles (Murcia) * Taras Banakh (Lviv) * Piotr Koszmider (Warsaw) * Mikołaj Krupski (Murcia / Warsaw) * Jorge López Abad (Madrid) [tentative] * Witold Marciszewski (Warsaw) * Arturo Martínez-Celis (Wroclaw) * Robert Rałowski (Wroclaw) * Grigor Sargsyan (Gdansk) * Jacek Tryba (Gdansk) All the informations about the conference can be found at https://es-pl.math.uni.lodz.pl/ In particular, here https://es-pl.math.uni.lodz.pl/second.pdf you can find the second announcement. The conference fee is 300 EUR (up to June 30). It covers conference materials, lunches, coffee breaks, excursions, reception on September 4th and banquet on September 7th. Ph.D. students have reduced fee (150 EUR). There is a possibility to give a contributed talk at the session. If you have any questions please do not hesitate to contact us. Your sincerely, Antonio Aviles, Piotr Borodulin-Nadzieja, Szymon Glab, Jaroslaw Swaczyna
Link to more info

Nankai Logic Colloquium

Nankai Logic Colloquium

lHello everyone,

This week our weekly Nankai Logic Colloquium is going to be in the afternoon.

Our speaker this week will be Maciej Malicki from Polish Academy of Sciences. This talk is going to take place this Friday,  May 12th,  from 4pm to 5pm(UTC+8, Beijing time). 

Title: Continuous logic and equivalence relations

Abstract: We will discuss two applications of infinitary continuous logic to Borel complexity of equivalence relations. We will characterize in model-theoretic terms essentially countable isomorphism relations on Borel classes of locally compact Polish metric structures. This gives a new proof of Kechris' theorem that orbit equivalence relations of actions of Polish locally compact groups are essentially countable. We will also show that isomorphism on such classes is always Borel reducible to graph isomorphism. This immediately answers a question of Gao and Kechris whether isometry of locally compact Polish metric spaces is reducible to graph isomorphism. The first result is joint work with Andreas Hallbäck and Todor Tsankov.


__________________________________________________________________________________________________

This is going to be an online event. Follow the link below to join the Zoom meeting. Please use your real name to join the meeting.

Title : The 28th Nankai Logic Colloquium --Maciej Malicki 
Time :16:00pm, May. 12, 2023 (Beijing Time) 
Zoom Number : 880 6946 7024
Passcode : 142863
_____________________________________________________________________


Best wishes,

Ming Xiao




Charla de Jose Moncayo en el Seminario Colombo Mexicano de Teoría de Conjuntos

Seminario Colombo Mexicano de Teoría de Conjuntos

Seminario Colombo Mexicano de Teoría de Conjuntos

 

Mayo 11

4:00 p.m. - 5:00 p.m. (hora de Colombia)  

 

Construcciones conjuntistas en modelos valuados y de Kripke

Jose R. Moncayo

Universidad Nacional de Colombia

 

Resumen. En esta charla se expondrán diferentes construcciones conjuntistas que buscan generalizar los modelos V y L en lógicas residuadas.

En primer lugar, usaremos la construcción de Scott y Solovay [1] (en donde se construye un modelo booleano de la teoría de conjuntos) para proponer dos definiciones de la noción de conjunto construible, tales que la primera terminará siendo isomorfa a V y la segunda a L.
En segundo lugar, mostraremos una generalización del trabajo de Fitting [2] sobre modelos de Kripke intuicionistas de la teoría de conjuntos. Para esto, se usarán los modelos de Kripke residuados de Ono y Komori [3, 4]. Propondremos una generalización de la jerarquía de von Neumann en el contexto de la lógica modal residuada y mostramos una traducción de fórmulas entre esta y una jerarquía de modelos Heyting valuados adecuados.

Referencias.
[1] Scott, D. & Solovay, R. (1967). Boolean-valued models for set theory.
[2] Fitting, M. (1969). Intuitionistic Logic, Model Theory and Forcing.
[3] Ono, H. & Komori, Y. (1985) Logics without the contraction rule.
[4] Ono, H. (1985) Semantical analysis of predicate logics without the contraction rule.

 

Zoom meeting information.

Meeting ID: 856 1882 0721

Passcode: 123456

https://cuaieed-unam.zoom.us/j/85618820721


This Week in Logic at CUNY

This Week in Logic at CUNY
This Week in Logic at CUNY:

- - - - Monday, May 8, 2023 - - - -

Saul Kripke Memorial Conference
The Saul Kripke Center and CUNY Graduate Center
May 8-9, 2023, 9am-5pm, The Elebash Recital Hall, Graduate Center, CUNY

Registration for attending in person is not required, but attendees will have to comply with the Graduate Center’s Building Access PolicyAlthough the conference will be a mainly in person event, a livestream is also available; for this, please register.

Lectures:
Romina Birman, Paul Boghossian, Harry Field, Melvin
Fitting, Daniel Isaacson, Carl Posy, Robert Stalnaker

Reminiscences:
Eduardo Barrio, James Burgess, David Chalmers, Mircea
Dumitru, Margaret Gilbert, Anandi Hattiangadi, Antonella
Mallozzi, Oliver Marshall, Yiannis Moschovakis, Stephen
Neale, Gary Ostertag, David Papineau, Graham Priest, Scott
Soames, Larry Tribe, Timothy Williamson

With an introduction by:
Steve Everett, Provost and Senior Vice President, The CUNY Graduate Center




- - - - Tuesday, May 9, 2023 - - - -

Saul Kripke Memorial Conference
The Saul Kripke Center and CUNY Graduate Center
May 8-9, 2023, 9am-5pm, The Elebash Recital Hall, Graduate Center, CUNY

Registration for attending in person is not required, but attendees will have to comply with the Graduate Center’s Building Access PolicyAlthough the conference will be a mainly in person event, a livestream is also available; for this, please register.

Lectures:
Romina Birman, Paul Boghossian, Harry Field, Melvin
Fitting, Daniel Isaacson, Carl Posy, Robert Stalnaker

Reminiscences:
Eduardo Barrio, James Burgess, David Chalmers, Mircea
Dumitru, Margaret Gilbert, Anandi Hattiangadi, Antonella
Mallozzi, Oliver Marshall, Yiannis Moschovakis, Stephen
Neale, Gary Ostertag, David Papineau, Graham Priest, Scott
Soames, Larry Tribe, Timothy Williamson

With an introduction by:
Steve Everett, Provost and Senior Vice President, The CUNY Graduate Center






Models of Peano Arithmetic (MOPA)
Tuesday, May 9, 1:00pm
Virtual (email Victoria Gitman vgitman@gmail.com for meeting id)

Mateusz Łełyk, University of Warsaw
Pathologies in Satisfaction Classes: part II

This is the second part of the talk given by Athar Abdul-Quader (Pathologically definable subsets of models of CT-), however we will make sure to make it self-contained.

The talk is centered around the following problem: when a subset of a countable and recursively saturated model M can be characterized as the set of the lengths of disjunctions on which a satisfaction class behaves correctly? More precisely: let DC(x) denote a sentence in a language of PA with a fresh binary predicate S which says 'For every disjunction d with at most x disjuncts and every assignment a, S(d,a) iff there is a disjunct d' in d such that S(d',a).' We say that X is a DC-set in (M,S) iff X is precisely the set of those numbers a such that (M,S) satisfies DC(a). We ask: given a countable and recursively saturated model M for which subsets X of M we can find a satisfaction class S such that X is a DC-set in (M,S)?

In the talk we study this problem for idempotent disjunctions, that is: disjunctions which repeat the same sentence. Let IDC(x) be DC(x) restricted to such 'idempotent' disjunctions of length x. The following is one of our core results:

Theorem: For an arbitrary countable and recursively saturated model M of PA the following conditions are equivalent:
(a) M is arithmetically saturated
(b) For every cut I in M there is a satisfaction class S such that I is an IDC-set in (M,S).

We study how this result generalizes to other propositional constructions in the place of disjunctions. The talk is based on a joint work with Athar Abdul-Quader presented in this paper from arxiv: arXiv:2303.18069v1 [math.LO] 31 Mar 2023.





- - - - Wednesday, May 10, 2023 - - - -

The Logic and Metaphysics Workshop special session
May 10th from 10:00-4:00 (NY time) 
CUNY Graduate Center, Kelly Skylight Room (in person)

10:00-11:30: Heinrich Wansing (Bochum)
Title: Quantifiers in connexive logic (in general and in particular)

Abstract: Connexive logic has room for two pairs of universal and particular quantifiers: one pair are standard quantifiers; the other pair are unorthodox, but we argue, are well-motivated in the context of connexive logic. Both non-standard quantifiers have been introduced previously, but in the context of connexive logic they have a natural semantic and proof-theoretic place, and plausible natural language readings. The result are logics which are negation inconsistent but non-trivial.
Note: This is joint work with Zach Weber (Otago).

12:30-2:00: Daniel Skurt (Bochum)
Title: RNmatrices for modal logics

Abstract: In this talk we will introduce a semantics for modal logics, based on so-called restricted Nmatrices (RNmatrices). These RNmatrices, previously used in the context of paraconsistent logics, prove to be a versatile tool for generating semantics for normal and non-normal systems of modal logics. Each of these semantics have sound and complete Hilbert-style calculi. The advantage of RNmatrices is that they provide a unifying framework for modal logics with or without first-order Kripke-frame conditions.
Note: This is joint work with Marcelo Coniglio (Campinas) and Pawel Pawlowski (Ghent).

2:30-4:00: Mark Colyvan (Sydney/LMU)
Title: Explanatory and non-explanatory proofs in mathematics

Abstract: In this paper I look at the contrast between explanatory and non-explanatory proofs in mathematics. This is done with the aim of shedding light on what distinguishes the explanatory proofs. I argue that there may be more than one notion of explanation in operation in mathematics: there does not seem to be a single account that ties together the different explanatory proofs found in mathematics. I then attempt to give a characterization of the different notions of explanation in play and how these sit with accounts of explanation found in philosophy of science.


- - - - Thursday, May 11, 2023 - - - -



- - - - Friday, May 12, 2023 - - - -

Logic Workshop
CUNY Graduate Center
Friday May 12, 2:00pm-3:30pm, Room 6417

Brian Wynne, CUNY
Recent developments in the model theory of Abelian lattice-ordered groups

An Abelian lattice-ordered group (-group) is an Abelian group with a partial ordering, invariant under translations, that is a lattice ordering. A prototypical example of an -group is , the continuous real-valued functions on the topological space  with pointwise operations and ordering. Let  be the class of -groups, viewed as structures for the first-order language . After giving more background on -groups, I will survey what is known about the -groups existentially closed (e.c.) in , including some new examples I constructed using Fraïssé limits. Then I will discuss some recently published work of Scowcroft concerning the -groups e.c. in , the class of nonzero Archimedean -groups with distinguished strong order unit (viewed as structures for ). Building on Scowcroft's results, I will present new axioms for the -groups e.c. in  and show how they allow one to characterize those spaces  for which  is e.c. in .



Next Week in Logic at CUNY:

- - - - Monday, May 15, 2023 - - - -

Logic and Metaphysics Workshop
Date: Monday, May 15, 4.15-6.15pm (NY time), GC 9206
NOTE: Meetings this semester are in person only (no zoom)
For meeting information, please sign up for our mailing list at https://logic.commons.gc.cuny.edu/about/

Maciej Sendłak (Warsaw).
Title: Explanatory realism and counterfactuals

Abstract: In my talk, I want to propose a novel approach to the question of counterfactuals. This is grounded in two assumptions, imported from the philosophy of science. The first one has it that to explain a phenomenon is to show how it depends on something else. The second states that the correct explanation ought to be contrastive. This means that a good explanation justifies the occurrence of a phenomenon and – at the same time – excludes occurrence of some other states of affairs. I am going to argue that – together with the assumption that conditionals express a dependence relation between A and C – the above gives ground for analysis of counterfactuals. According to this proposal: “A>C” is true at the world of evaluation iff there is a relation of dependence that hold between referents of A and C, and the same relation of dependence holds in the world of evaluation.





- - - - Tuesday, May 16, 2023 - - - -



- - - - Wednesday, May 17, 2023 - - - -

The New York City Category Theory Seminar
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York

Speaker:     Arthur Parzygnat, Nagoya University.

Date and Time:     Wednesday May 17, 2023, 7:00 - 8:30 PM. IN PERSON TALK.

Title:     Inferring the past and using category theory to define retrodiction.


Abstract: Classical retrodiction is the act of inferring the past based on knowledge of the present. The primary example is given by Bayes' rule P(y|x) P(x) = P(x|y) P(y), where we use prior information, conditional probabilities, and new evidence to update our belief of the state of some system. The question of how to extend this idea to quantum systems has been debated for many years. In this talk, I will lay down precise axioms for (classical and quantum) retrodiction using category theory. Among a variety of proposals for quantum retrodiction used in settings such as thermodynamics and the black hole information paradox, only one satisfies these categorical axioms. Towards the end of my talk, I will state what I believe is the main open question for retrodiction, formalized precisely for the first time. This work is based on the preprint https://arxiv.org/abs/2210.13531 and is joint work with Francesco Buscemi.





- - - - Thursday, May 18, 2023 - - - -



- - - - Friday, May 19, 2023 - - - -

Set Theory Seminar
CUNY Graduate Center
Friday, May 19, 12:30pm NY time
Virtual: Please email Victoria Gitman (vgitman@gmail.com) for meeting id.

Miha Habič, Bard College at Simon's Rock
Some old and new results on nonamalgamable forcing extensions

Fixing some countable transitive model  of set theory, we can consider its generic multiverse, the family of all models obtainable from  by taking any sequence of forcing extensions and ground models. There is an attractive similarity between the generic multiverse and the Turing degrees, but the multiverse has the drawback (or feature?) that it contains nonamalgamable models, that is, models with no common upper bound, as was observed by several people, going back to at least Mostowski. In joint work with Hamkins, Klausner, Verner, and Williams in 2019, we studied the order-theoretic properties of the generic multiverse and, among other results, gave a characterization of which partial orders embed nicely into the multiverse. I will present our results in the simplest case of Cohen forcing, as well as existing generalizations to wide forcing, and some new results on non-Cohen ccc forcings.






- - - - Other Logic News - - - -


- - - - Web Site - - - -

Find us on the web at:  nylogic.github.io
(site designed, built & maintained by Victoria Gitman)

--------  ADMINISTRIVIA  --------

To subscribe/unsubscribe to this list, please email your request to jreitz@citytech.cuny.edu.

If you have a logic-related event that you would like included in future mailings, please email jreitz@citytech.cuny.edu.

(KGRC) Set Theory Seminar talk on TUESDAY, May 9

Kurt Godel Research Center
The KGRC welcomes as guests: Clifton Ealy (host: Matthias Aschenbrenner) visits the KGRC until August 15. Thilo Weinert (host: Vera Fischer) visits the KGRC until June 30 and gives a talk, see below. Sergei Starchenko (host: Matthias Aschenbrenner) visits the KGRC from May 13 to May 27 and gives a talk, details to be announced at a later time. Fabian Kaak (host: Vera Fischer) visits the KGRC from May 23 to May 26 and gives a short talk, details to be announced at a later time. Ido Feldman (host: Miguel Moreno) visits the KGRC from June 11 to June 17 and gives a talk, details to be announced at a later time. Jaroslav Šupina (host: Vera Fischer) visits the KGRC from June 18 to June 24 and gives a talk, details to be announced at a later time. Nadiya Kolos (host: Miguel Moreno) visits the KGRC from June 19 to June 23 and gives a talk, details to be announced at a later time. * * * Set Theory Seminar Kurt Gödel Research Center TUESDAY, May 9 (Please note the unusual day and the time!) "On Unsound Linear Orderings" Thilo Weinert In the Eighties Adrian Mathias introduced the notion of soundness of an ordinal. An ordinal is sound if for any countable partition P of it only countably many ordinals are order-types of unions of subpartitionts of P. Mathias showed that the least unsound ordinal $\zeta$ is $\omega_1^{\omega + 2}$ if $\aleph_1$ can be embedded into the continuum but if $\aleph_1$ is regular yet cannot be embedded into the continuum, $\zeta \geqslant \omega_1^{\omega 2 + 1}$. I am going to discuss his findings and consider the notion for the more general class of linear orderings building on work by him, MacPherson, and Schmerl. I am also going to mention some open problems. This is joint ongoing work with Garrett Ervin and Jonathan Schilhan. Time and Place Talk at 3:00pm in hybrid mode: on-site as well as via Zoom Universität Wien Institut für Mathematik Kolingasse 14-16 1090 Wien 1st floor Seminar room 10 Zoom: If you need the Zoom data and have not received the meeting link by the day before the talk, please contact richard.springer@univie.ac.at! Please direct any other questions about this talk to vera.fischer@univie.ac.at.

Wednesday seminar

Prague Set Theory Seminar
Dear all, The seminar meets on Wednesday May 10th at 11:00 in the Institute of Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building. There will be no seminars during a couple of weeks after next the next one. The seminar will more likely meet again on Wednesday June 21st. Program: Tomas Jakl -- Game comonads and the composition methods Composition methods are a key technique in finite model theory, which enables modular reasoning about complex structures. Examples of such theorems are Mostowski theorem and Feferman-Vaught theorems, which express that logical equivalence of structures is congruent with respect to the operations of disjoint union and products of structures. Typical applications of composition methods in finite model theory are Courcelle's algorithmic meta theorems. In this talk I will give a brief overview of game comonads, a new tool from category theory in finite model theory, and discuss how they allow us to prove very general Feferman-Vaught-Mostowski theorems. Comonads are the formally dual notion to monads, where the latter can be used to describe algebraic systems over arbitrary domains. For example, topological groups can be viewed as algebras over topological spaces. Game comonads are an approach to creating comonads by semantically encoding a game-theoretic description of logical equivalence. Our approach allows us to make use of a categorical description of tensor products and bilinear maps of vector spaces. Best, David

Logic Seminar 10 May 2023 17:00 hrs at NUS by Jan Baars

NUS Logic Seminar
Invitation to the Logic Seminar at the National University of Singapore Date: Wednesday, 10 May 2023, 17:00 hrs Place: NUS, Department of Mathematics, S17#04-05 Speaker: Jan Baars Title: Generalisations of a result by Gulko on spaces of continuous functions URL: http://www.comp.nus.edu.sg/~fstephan/logicseminar.html Please find the abstract attached.

Cross-Alps Logic Seminar (speaker: Dima Sinapova)

Cross-Alps Logic Seminar
On Friday 05.05.2023 at 16.00
Dima Sinapova (Rutgers University)
will give a talk on 
Mutual stationarity and the failure of SCH

Please refer to the usual webpage of our LogicGroup for more details and the abstract of the talk.
The seminar will be held remotely through Webex. Please write to vincenzo.dimonte [at] uniud [dot] it for the link to the event.

The Cross-Alps Logic Seminar is co-organized by the logic groups of Genoa, Lausanne, Turin and Udine as part of our collaboration in the project PRIN 2017 'Mathematical logic: models, sets, computability'.

All the best,
Vincenzo

Charla de Joel Aguilar en el Seminario Colombo Mexicano de Teoría de Conjuntos

Seminario Colombo Mexicano de Teoría de Conjuntos

Seminario Colombo Mexicano de Teoría de Conjuntos

 

Mayo 4

4:00 p.m. - 5:00 p.m. (hora de Colombia)  

 

Subespacios "grandes" de C_p(X) y sus invariantes cardinales

Joel Aguilar

Universidad Michoacana de San Nicolás de Hidalgo

 

Resumen. Sea C_p(X) el espacio de funciones continuas de X en R con la topología de la convergencia puntual (para garantizar que C_p(X) sea no trivial en esta plática asumiremos que todos los espacios estudiados son de Tychonoff). Una técnica común para obtener información de un espacio X es estudiar las propiedades de sus subespacios "suficientemente grandes"; por ejemplo, un espacio con un subespacio denso y psuedocompacto tiene que ser pseudocompacto; un espacio no puede ser de Lindelöf si tiene un subespacio no-numerable, discreto y cerrado; etc. En la plática nos enfocaremos en los subespacios de C_p(X) que también son densos en la topología uniforme y discutiremos cómo se relacionan las propiedades de estos subespacios con las de C_p(X).

 

Zoom meeting information.

Meeting ID: 856 1882 0721

Passcode: 123456

https://cuaieed-unam.zoom.us/j/85618820721


Nankai Logic Colloquium

Nankai Logic Colloquium

Hello everyone,

Sorry for the interrupting again. I would like to apologize(again) for a mistake in the previous announcement. There was a serious mistake in the time mentioned. The correct time of the Nankai Logic Colloquium this week is in the afternoon, 4pm to 5pm (instead of morning mentioned in the last email), Friday Beijing time. I am very very sorry for the confuse it may cause.

The following is a corrected version of the announcement for this week:

_____________________________________________________

This week our weekly Nankai Logic Colloquium is going to be in the afternoon.

Our speaker this week will be Ilijas Farah from York University. This talk is going to take place this Friday,  May 5th,  from 4pm to 5pm(UTC+8, Beijing time). 

Title:  Corona rigidity


Abstract. Reduced powers associated with the Frech\'et filter are well-known to be countably saturated (that is, $\aleph_1$-saturated). Because of this the Continuum Hypothesis implies that the reduced power of every countable structure has $2^{2^{\aleph_0}}$ automorphisms, and that for such reduced powers elementary equivalence is a sufficient condition for isomorphism. On the other hand, forcing axioms imply that some reduced powers (e.g., those of finite Boolean algebras) have only trivial automorphisms while some other reduced powers are saturated and they $2^{2^{\aleph_0}}$ automorphisms, provably in ZFC (e.g., those of the 2-element cyclic group).

This begs two questions: Which structures have saturated reduced powers, provably in ZFC? For which structures forcing axioms imply the `corona rigidity', that their reduced powers have only trivial automorphisms?
I will give a complete answer to the first question and a partial (rather surprising) answer to the second.

__________________________________________________________________________________________________

This is going to be an online event. Follow the link below to join the Zoom meeting. Please use your real name to join the meeting.

Title : The 27th Nankai Logic Colloquium --Ilijas Farah
Time :16:00pm, May. 05, 2023 (Beijing Time) 
Zoom Number : 827 3827 3373
Passcode : 821730
Link :https://us02web.zoom.us/j/82738273373?pwd=ZnFYbEFUSWErcDVROFUrQnZ1WGNxZz09
_____________________________________________________________________


Best wishes,

Ming Xiao






Wednesday seminar

Prague Set Theory Seminar
Dear all, The seminar meets on Wednesday May 3rd at 11:00 in the Institute of Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building. There is no fixed program yet. We will meet and see what are we interested in hearing/working on. Walk-in speakers are welcome. Best, David

Nankai Logic Colloquium

Nankai Logic Colloquium

Hello everyone,

I would like to apologize for a mistake in the previous announcement. There was a typo in the time mentioned. The correct time is 9am to 10am (instead of 10pm). I am very sorry for the confuse it may cause.

The following is a corrected version of the previous email:

_____________________________________________________

This week our weekly Nankai Logic Colloquium is going to be in the morning.

Our speaker this week will be Ilijas Farah from York University. This talk is going to take place this Friday,  May 5th,  from 9am to 10am(UTC+8, Beijing time). 

Title:  Corona rigidity


Abstract. Reduced powers associated with the Frech\'et filter are well-known to be countably saturated (that is, $\aleph_1$-saturated). Because of this the Continuum Hypothesis implies that the reduced power of every countable structure has $2^{2^{\aleph_0}}$ automorphisms, and that for such reduced powers elementary equivalence is a sufficient condition for isomorphism. On the other hand, forcing axioms imply that some reduced powers (e.g., those of finite Boolean algebras) have only trivial automorphisms while some other reduced powers are saturated and they $2^{2^{\aleph_0}}$ automorphisms, provably in ZFC (e.g., those of the 2-element cyclic group).

This begs two questions: Which structures have saturated reduced powers, provably in ZFC? For which structures forcing axioms imply the `corona rigidity', that their reduced powers have only trivial automorphisms?
I will give a complete answer to the first question and a partial (rather surprising) answer to the second.

__________________________________________________________________________________________________

This is going to be an online event. Follow the link below to join the Zoom meeting. Please use your real name to join the meeting.

Title : The 27th Nankai Logic Colloquium --Ilijas Farah
Time :9:00am, May. 05, 2023 (Beijing Time) 
Zoom Number : 827 3827 3373
Passcode : 821730
Link :https://us02web.zoom.us/j/82738273373?pwd=ZnFYbEFUSWErcDVROFUrQnZ1WGNxZz09
_____________________________________________________________________


Best wishes,

Ming Xiao





Nankai Logic Colloquium

Nankai Logic Colloquium

Hello everyone,

This week our weekly Nankai Logic Colloquium is going to be in the morning.

Our speaker this week will be Ilijas Farah from York University. This talk is going to take place this Friday,  May 5th,  from 9am to 10pm(UTC+8, Beijing time). 

Title:  Corona rigidity


Abstract. Reduced powers associated with the Frech\'et filter are well-known to be countably saturated (that is, $\aleph_1$-saturated). Because of this the Continuum Hypothesis implies that the reduced power of every countable structure has $2^{2^{\aleph_0}}$ automorphisms, and that for such reduced powers elementary equivalence is a sufficient condition for isomorphism. On the other hand, forcing axioms imply that some reduced powers (e.g., those of finite Boolean algebras) have only trivial automorphisms while some other reduced powers are saturated and they $2^{2^{\aleph_0}}$ automorphisms, provably in ZFC (e.g., those of the 2-element cyclic group).

This begs two questions: Which structures have saturated reduced powers, provably in ZFC? For which structures forcing axioms imply the `corona rigidity', that their reduced powers have only trivial automorphisms?
I will give a complete answer to the first question and a partial (rather surprising) answer to the second.

__________________________________________________________________________________________________

This is going to be an online event. Follow the link below to join the Zoom meeting. Please use your real name to join the meeting.

Title : The 27th Nankai Logic Colloquium --Ilijas Farah
Time :9:00am, May. 05, 2023 (Beijing Time) 
Zoom Number : 827 3827 3373
Passcode : 821730
Link :https://us02web.zoom.us/j/82738273373?pwd=ZnFYbEFUSWErcDVROFUrQnZ1WGNxZz09
_____________________________________________________________________


Best wishes,

Ming Xiao




This Week in Logic at CUNY

This Week in Logic at CUNY
This Week in Logic at CUNY:

- - - - Monday, May 1, 2023 - - - -

Logic and Metaphysics Workshop
Date: Monday, May 1, 4.15-6.15pm (NY time), GC 9206
NOTE: Meetings this semester are in person only (no zoom)
For meeting information, please sign up for our mailing list at https://logic.commons.gc.cuny.edu/about/
Samara Burns (Columbia).
Title: Understanding (and) surveyability

Abstract: In this talk I will discuss the notion of surveyable proof. Discussions of surveyability emerge periodically in recent philosophical literature, but the notion of surveyable proof can be traced back to Descartes. Despite this long history, there is still disagreement about what features a proof must have in order to count as surveyable. This disagreement arises, in part, because there is still significant vagueness regarding the problem that unsurveyability poses for the epistemology of mathematics. I identify three features of justification in mathematics that could be at issue in the surveyability debate: a priority, internalism, and certainty. Each of these features is prima facie troubled by unsurveyable proof. In each case, however, I’ll argue that unsurveyable proof does not pose any real issue. I will suggest that the surveyability debate should not be framed in terms of justification at all, and that the problem is really about mathematical understanding.



- - - - Tuesday, May 2, 2023 - - - -



- - - - Wednesday, May 3, 2023 - - - -

The New York City Category Theory Seminar
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York

Speaker:     Gemma De las Cuevas, University of Innsbruck.

Date and Time:     Wednesday May 3, 2023, 7:00 - 8:30 PM. ZOOM TALK.

Title:     A framework for universality across disciplines.


Abstract: What is the scope of universality across disciplines? And what is its relation to undecidability? To address these questions, we build a categorical framework for universality. Its instances include Turing machines, spin models, and others. We introduce a hierarchy of universality and argue that it distinguishes universal Turing machines as a non-trivial form of universality. We also outline the relation to undecidability by drawing a connection to Lawvere’s Fixed Point Theorem. Joint work with Sebastian Stengele, Tobias Reinhart and Tomas Gonda.





- - - - Thursday, May 4, 2023 - - - -



- - - - Friday, May 5, 2023 - - - -

Set Theory Seminar
CUNY Graduate Center
NOTE UPDATED TIME: Friday, May 5, 10:00am NY time
Virtual: Please email Victoria Gitman (vgitman@gmail.com) for meeting id.
Joel David Hamkins, Notre Dame University

Realizing Frege's Basic Law V, provably in ZFC

The standard set-theoretic distinction between sets and classes instantiates in important respects the Fregean distinction between objects and concepts, for in set theory we commonly take the universe of sets as a realm of objects to be considered under the guise of diverse concepts, the definable classes, each serving as a predicate on that domain of individuals. Although it is commonly held that in a very general manner, there can be no association of classes with objects in a way that fulfills Frege's Basic Law V, nevertheless, in the ZF framework, it turns out that we can provide a completely deflationary account of this and other Fregean abstraction principles. Namely, there is a mapping of classes to objects, definable in set theory in senses I shall explain (hence deflationary), associating every first-order parametrically definable class  with a set object , in such a way that Basic Law V is fulfilled:
Russell's elementary refutation of the general comprehension axiom, therefore, is improperly described as a refutation of Basic Law V itself, but rather refutes Basic Law V only when augmented with powerful class comprehension principles going strictly beyond ZF. The main result leads also to a proof of Tarski's theorem on the nondefinability of truth as a corollary to Russell's argument. A central goal of the project is to highlight the issue of definability and deflationism for the extension assignment problem at the core of Fregean abstraction.



Logic Workshop
CUNY Graduate Center
Friday May 5, 2:00pm-3:30pm, Room 6417
Karen Lange, Wellesley College

Classification via effective lists

'Classifying' a natural collection of structures is a common goal in mathematics. Providing a classification can mean different things, e.g., identifying a set of invariants that settle the isomorphism problem or creating a list of all structures of a given kind without repetition of isomorphism type. Here we discuss recent work on classifications of the latter kind from the perspective of computable structure theory. We’ll consider natural classes of computable structures such as vector spaces, equivalence relations, algebraic fields, and trees to better understand the nuances of classification via effective lists and its relationship to other forms of classification in this setting.



Next Week in Logic at CUNY:

- - - - Monday, May 8, 2023 - - - -

Saul Kripke Memorial Conference
The Saul Kripke Center and CUNY Graduate Center
May 8-9, 2023, 9am-5pm, The Elebash Recital Hall, Graduate Center, CUNY

Registration for attending in person is not required, but attendees will have to comply with the Graduate Center’s Building Access PolicyAlthough the conference will be a mainly in person event, a livestream is also available; for this, please register.

Lectures:
Romina Birman, Paul Boghossian, Harry Field, Melvin
Fitting, Daniel Isaacson, Carl Posy, Robert Stalnaker

Reminiscences:
Eduardo Barrio, James Burgess, David Chalmers, Mircea
Dumitru, Margaret Gilbert, Anandi Hattiangadi, Antonella
Mallozzi, Oliver Marshall, Yiannis Moschovakis, Stephen
Neale, Gary Ostertag, David Papineau, Graham Priest, Scott
Soames, Larry Tribe, Timothy Williamson

With an introduction by:
Steve Everett, Provost and Senior Vice President, The CUNY Graduate Center




- - - - Tuesday, May 9, 2023 - - - -

Saul Kripke Memorial Conference
The Saul Kripke Center and CUNY Graduate Center
May 8-9, 2023, 9am-5pm, The Elebash Recital Hall, Graduate Center, CUNY

Registration for attending in person is not required, but attendees will have to comply with the Graduate Center’s Building Access PolicyAlthough the conference will be a mainly in person event, a livestream is also available; for this, please register.

Lectures:
Romina Birman, Paul Boghossian, Harry Field, Melvin
Fitting, Daniel Isaacson, Carl Posy, Robert Stalnaker

Reminiscences:
Eduardo Barrio, James Burgess, David Chalmers, Mircea
Dumitru, Margaret Gilbert, Anandi Hattiangadi, Antonella
Mallozzi, Oliver Marshall, Yiannis Moschovakis, Stephen
Neale, Gary Ostertag, David Papineau, Graham Priest, Scott
Soames, Larry Tribe, Timothy Williamson

With an introduction by:
Steve Everett, Provost and Senior Vice President, The CUNY Graduate Center






Models of Peano Arithmetic (MOPA)
Tuesday, May 9, 1:00pm
Virtual (email Victoria Gitman vgitman@gmail.com for meeting id)

Mateusz Łełyk, University of Warsaw
Pathologies in Satisfaction Classes: part II

This is the second part of the talk given by Athar Abdul-Quader (Pathologically definable subsets of models of CT-), however we will make sure to make it self-contained.

The talk is centered around the following problem: when a subset of a countable and recursively saturated model M can be characterized as the set of the lengths of disjunctions on which a satisfaction class behaves correctly? More precisely: let DC(x) denote a sentence in a language of PA with a fresh binary predicate S which says 'For every disjunction d with at most x disjuncts and every assignment a, S(d,a) iff there is a disjunct d' in d such that S(d',a).' We say that X is a DC-set in (M,S) iff X is precisely the set of those numbers a such that (M,S) satisfies DC(a). We ask: given a countable and recursively saturated model M for which subsets X of M we can find a satisfaction class S such that X is a DC-set in (M,S)?

In the talk we study this problem for idempotent disjunctions, that is: disjunctions which repeat the same sentence. Let IDC(x) be DC(x) restricted to such 'idempotent' disjunctions of length x. The following is one of our core results:

Theorem: For an arbitrary countable and recursively saturated model M of PA the following conditions are equivalent:
(a) M is arithmetically saturated
(b) For every cut I in M there is a satisfaction class S such that I is an IDC-set in (M,S).

We study how this result generalizes to other propositional constructions in the place of disjunctions. The talk is based on a joint work with Athar Abdul-Quader presented in this paper from arxiv: arXiv:2303.18069v1 [math.LO] 31 Mar 2023.





- - - - Wednesday, May 10, 2023 - - - -

The Logic and Metaphysics Workshop special session
May 10th from 10:00-4:00 (NY time) 
CUNY Graduate Center, Kelly Skylight Room (in person)

10:00-11:30: Heinrich Wansing (Bochum)
Title: Quantifiers in connexive logic (in general and in particular)

Abstract: Connexive logic has room for two pairs of universal and particular quantifiers: one pair are standard quantifiers; the other pair are unorthodox, but we argue, are well-motivated in the context of connexive logic. Both non-standard quantifiers have been introduced previously, but in the context of connexive logic they have a natural semantic and proof-theoretic place, and plausible natural language readings. The result are logics which are negation inconsistent but non-trivial.
Note: This is joint work with Zach Weber (Otago).

12:30-2:00: Daniel Skurt (Bochum)
Title: RNmatrices for modal logics

Abstract: In this talk we will introduce a semantics for modal logics, based on so-called restricted Nmatrices (RNmatrices). These RNmatrices, previously used in the context of paraconsistent logics, prove to be a versatile tool for generating semantics for normal and non-normal systems of modal logics. Each of these semantics have sound and complete Hilbert-style calculi. The advantage of RNmatrices is that they provide a unifying framework for modal logics with or without first-order Kripke-frame conditions.
Note: This is joint work with Marcelo Coniglio (Campinas) and Pawel Pawlowski (Ghent).

2:30-4:00: Mark Colyvan (Sydney/LMU)
Title: Explanatory and non-explanatory proofs in mathematics

Abstract: In this paper I look at the contrast between explanatory and non-explanatory proofs in mathematics. This is done with the aim of shedding light on what distinguishes the explanatory proofs. I argue that there may be more than one notion of explanation in operation in mathematics: there does not seem to be a single account that ties together the different explanatory proofs found in mathematics. I then attempt to give a characterization of the different notions of explanation in play and how these sit with accounts of explanation found in philosophy of science.


- - - - Thursday, May 11, 2023 - - - -



- - - - Friday, May 12, 2023 - - - -

Logic Workshop
CUNY Graduate Center
Friday May 12, 2:00pm-3:30pm, Room 6417

Brian Wynne, CUNY
Recent developments in the model theory of Abelian lattice-ordered groups

An Abelian lattice-ordered group (-group) is an Abelian group with a partial ordering, invariant under translations, that is a lattice ordering. A prototypical example of an -group is , the continuous real-valued functions on the topological space  with pointwise operations and ordering. Let  be the class of -groups, viewed as structures for the first-order language . After giving more background on -groups, I will survey what is known about the -groups existentially closed (e.c.) in , including some new examples I constructed using Fraïssé limits. Then I will discuss some recently published work of Scowcroft concerning the -groups e.c. in , the class of nonzero Archimedean -groups with distinguished strong order unit (viewed as structures for ). Building on Scowcroft's results, I will present new axioms for the -groups e.c. in  and show how they allow one to characterize those spaces  for which  is e.c. in .



- - - - Other Logic News - - - -

CONFERENCE ANNOUNCEMENT
Saul Kripke Memorial Conference
May 8-9, 2023
The Saul Kripke Center and CUNY Graduate Center

The Saul Kripke Center will host a memorial conference honoring Saul Kripke (1940-2022) at The CUNY Graduate Center on May 8th and 9th, 2023. The conference program is available here. Registration for attending in person is not required, but attendees will have to comply with the Graduate Center’s Building Access Policy. Although the conference will be a mainly in person event, a livestream is also available; for this, please register.



- - - - Web Site - - - -

Find us on the web at:  nylogic.github.io
(site designed, built & maintained by Victoria Gitman)

--------  ADMINISTRIVIA  --------

To subscribe/unsubscribe to this list, please email your request to jreitz@citytech.cuny.edu.

If you have a logic-related event that you would like included in future mailings, please email jreitz@citytech.cuny.edu.

(KGRC) two talks on Thursday, May 4

Kurt Godel Research Center
The KGRC welcomes as guests: Clifton Ealy (host: Matthias Aschenbrenner) visits the KGRC until August 15. Heike Mildenberger (host: Vera Fischer) visits the KGRC from May 3 to May 6 and gives a talk on May 4, see below. Fabian Kaak (host: Vera Fischer) visits the KGRC from May 23 to May 26 and gives a short talk, details to be announced at a later time. Ido Feldman (host: Miguel Moreno) visits the KGRC from June 11 to June 17 and gives a talk, details to be announced at a later time. Jaroslav Šupina (host: Vera Fischer) visits the KGRC from June 18 to June 24 and gives a talk, details to be announced at a later time. Nadiya Kolos (host: Miguel Moreno) visits the KGRC from June 19 to June 23 and gives a talk, details to be announced at a later time. * * * Set Theory Seminar Kurt Gödel Research Center Thursday, May 4 "Coding with localization forcing and generalized descriptive set theory" Lyubomyr Zdomskyy (TU Wien) There are many known ways how to make various objects definable by designing a suitable description for them with the help of forcing. One of such methods is based on so-called localization invented by R. David and further developed by S. Friedman, V. Fischer, D. Schrittesser, and many others. We shall discuss the application of this method to the study of Borel* subsets of 2^kappa for a successor cardinal kappa. Joint work with Miguel Moreno. Time and Place Talk at 11:30am in hybrid mode: on-site as well as via Zoom Universität Wien Institut für Mathematik Kolingasse 14-16 1090 Wien 1st floor Seminar room 10 Zoom: If you need the Zoom data and have not received the meeting link by the day before the talk, please contact richard.springer@univie.ac.at! Please direct any other questions about this talk to vera.fischer@univie.ac.at. * * * Logic Colloquium Kurt Gödel Research Center Thursday, May 4 "Destroying Guessing Principles" Heike Mildenberger (University of Freiburg, DE) An Ostaszewski club sequence is a weakening of Jensen's diamond. In contrast to the diamond, the club does not imply the continuum hypothesis. Numerous questions about the club stay open, and we know only few models in which there is just a club sequence but no diamond sequence. In recent joint work with Shelah we found that a winning strategy for the completeness player in a bounding game on a forcing order does not suffice to establish the club in the extension. Time and Place Talk at 3:00pm in hybrid mode: on-site as well as via Zoom Universität Wien Institut für Mathematik Oskar-Morgenstern-Platz 1 1090 Wien 2nd floor room HS 11 Zoom: If you need the Zoom data and have not received the meeting link by the day before the talk, please contact richard.springer@univie.ac.at! Please direct any other questions about this talk to vera.fischer@univie.ac.at.

Charla de Diana Montoya en el Seminario Colombo Mexicano de Teoría de Conjuntos

Seminario Colombo Mexicano de Teoría de Conjuntos

Seminario Colombo Mexicano de Teoría de Conjuntos

 

Abril 27

4:00 p.m. - 5:00 p.m. (hora de Colombia)  

 

Cardinales característicos en el caso no enumerable
Diana C. Montoya

Universidad Técnica de Viena

 

Resumen. En la primera parte de esta charla, presentaré la motivación y algunos resultados generales de la teoría de cardinales característicos en los espacios de Baire generalizados $\kappa^\kappa$; asimismo, presentaré un resumen del estado del arte actual de este tema. En la segunda parte, me enfocaré en el concepto de independencia maximal en estos espacios para el caso en el cual $\kappa$ es un cardinal regular (medible), y también en el caso en el que $\kappa$ es singular. Al final, mencionaré algunas preguntas abiertas y futuras líneas de investigación. 


Zoom meeting information.
Meeting ID: 856 1882 0721
Passcode: 123456

Nankai Logic Colloquium

Nankai Logic Colloquium

Hello everyone,

This week our weekly Nankai Logic Colloquium is going to be in the morning.

Our speaker this week will be Ronnie Chen from the University of Michigan. This talk is going to take place this Friday,  Apr 28th,  from 9am to 10pm(UTC+8, Beijing time). 

Title: Topology versus Borel structure for actions

Abstract: A "nice" (e.g., Polish) topology contains a lot more structure than its induced Borel $\sigma$-algebra. On the other hand, Pettis's theorem says that a Polish group topology is completely determined by its induced Borel group structure. The Becker--Kechris theorem interpolates between these two extreme behaviors in the context of group actions, by characterizing the compatible topologies on a Borel $G$-space. We give a new proof of a strengthened version of the core ingredient in the Becker--Kechris theorem, that clarifies its connection to several other results in the theory of Polish group actions, as well as generalizing cleanly to other contexts such as non-Hausdorff spaces, Borel first-order $G$-structures, and groupoid actions.

__________________________________________________________________________________________________

This is going to be an online event. Follow the link below to join the Zoom meeting. Please use your real name to join the meeting.

Title : The 26th Nankai Logic Colloquium --Ronnie Chen

Time :9:00am, Apr. 28, 2023 (Beijing Time) 

Zoom Number : 840 0998 2925

Passcode : 553830

_____________________________________________________________________


Best wishes,

Ming Xiao




This Week in Logic at CUNY

This Week in Logic at CUNY
This Week in Logic at CUNY:

- - - - Monday, Apr 24, 2023 - - - -

Rutgers Logic Seminar 
Monday, April 24, 2pm, Rutgers University, Hill 005
Aristotelis Panagiotopoulos, CMU


Logic and Metaphysics Workshop
Date: Monday, April 24, 4.15-6.15pm (NY time), GC 9206
NOTE: Meetings this semester are in person only (no zoom)
For meeting information, please sign up for our mailing list at https://logic.commons.gc.cuny.edu/about/
Andrea Iacona (Turin).
Title: Inferentialism and connexivity

Abstract: In my talk I will investigate the relationships between two claims about conditionals that by and large are discussed separately. One is the claim that a conditional holds when its consequent can be inferred from its antecedent, or when the latter provides a reason for accepting the former. The other is the claim that conditionals intuitively obey some characteristic connexive principles, such as Aristotle’s Thesis and Boethius Thesis. Following a line of thought that goes back to Chrysippus, I will suggest that these two claims may coherently be understood as distinct manifestations of a single basic idea, namely, that a conditional holds when its antecedent is incompatible with the negation of its consequent. The account of conditionals that I will outline is based precisely on this idea.



- - - - Tuesday, Apr 25, 2023 - - - -

Models of Peano Arithmetic (MOPA)
Tuesday, April 25, 1:00pm
Virtual (email Victoria Gitman vgitman@gmail.com for meeting id)
Mateusz Łełyk University of Warsaw

Pathologies in Satisfaction Classes

This is the second part of the talk given by Athar Abdul-Quader (Pathologically definable subsets of models of CT-), however we will make sure to make it self-contained.

The talk is centered around the following problem: when a subset of a countable and recursively saturated model M can be characterized as the set of the lengths of disjunctions on which a satisfaction class behaves correctly? More precisely: let DC(x) denote a sentence in a language of PA with a fresh binary predicate S which says 'For every disjunction d with at most x disjuncts and every assignment a, S(d,a) iff there is a disjunct d' in d such that S(d',a).' We say that X is a DC-set in (M,S) iff X is precisely the set of those numbers a such that (M,S) satisfies DC(a). We ask: given a countable and recursively saturated model M for which subsets X of M we can find a satisfaction class S such that X is a DC-set in (M,S)?

In the talk we study this problem for idempotent disjunctions, that is: disjunctions which repeat the same sentence. Let IDC(x) be DC(x) restricted to such 'idempotent' disjunctions of length x. The following is one of our core results:

Theorem: For an arbitrary countable and recursively saturated model M of PA the following conditions are equivalent:
(a) M is arithmetically saturated
(b) For every cut I in M there is a satisfaction class S such that I is an IDC-set in (M,S).

We study how this result generalizes to other propositional constructions in the place of disjunctions. The talk is based on a joint work with Athar Abdul-Quader presented in this paper from arxiv: arXiv:2303.18069v1 [math.LO] 31 Mar 2023.




- - - - Wednesday, Apr 26, 2023 - - - -

The New York City Category Theory Seminar
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York

Speaker:     Dusko Pavlovic, University of Hawai‘i at Mānoa.

Date and Time:     Wednesday April 26, 2023, 7:00 - 8:30 PM. ZOOM TALK.

Title:     Program-closed categories.


Abstract: > Let CC be a symmetric monoidal category with a comonoid on every object. Let CC* be the cartesian subcategory with the same objects and just the comonoid homomorphisms. A *programming language* is a well-ordered object P with a *program closure*: a family of X-natural surjections
CC(XA,B) <<--run_X-- CC*(X,P)
one for every pair A,B. In this talk, I will sketch a proof that program closure is a property: Any two programming languages are isomorphic along run-preserving morphisms. The result counters Kleene's interpretation of the Church-Turing Thesis, which has been formalized categorically as the suggestion that computability is a structure, like a group presentation, and not a property, like completeness. We prove that it is like completeness. The draft of a book on categorical computability is available from the web site dusko.org.




- - - - Thursday, Apr 27, 2023 - - - -



- - - - Friday, Apr 28, 2023 - - - -

Set Theory Seminar
CUNY Graduate Center
Friday, April 28, 12:15pm NY time
Virtual: Please email Victoria Gitman (vgitman@gmail.com) for meeting id.
Will Boney Texas State University



Next Week in Logic at CUNY:

- - - - Monday, May 1, 2023 - - - -



- - - - Tuesday, May 2, 2023 - - - -



- - - - Wednesday, May 3, 2023 - - - -

The New York City Category Theory Seminar
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York

Speaker:     Gemma De las Cuevas, University of Innsbruck.

Date and Time:     Wednesday May 3, 2023, 7:00 - 8:30 PM. ZOOM TALK.

Title:     A framework for universality across disciplines.


Abstract: What is the scope of universality across disciplines? And what is its relation to undecidability? To address these questions, we build a categorical framework for universality. Its instances include Turing machines, spin models, and others. We introduce a hierarchy of universality and argue that it distinguishes universal Turing machines as a non-trivial form of universality. We also outline the relation to undecidability by drawing a connection to Lawvere’s Fixed Point Theorem. Joint work with Sebastian Stengele, Tobias Reinhart and Tomas Gonda.





- - - - Thursday, May 4, 2023 - - - -



- - - - Friday, May 5, 2023 - - - -

Set Theory Seminar
CUNY Graduate Center
Friday, May 5, 12:15pm NY time
Virtual: Please email Victoria Gitman (vgitman@gmail.com) for meeting id.
Joel David Hamkins Notre Dame University



Logic Workshop
CUNY Graduate Center
Friday May 5, 2:00pm-3:30pm, Room 6417
Karen Lange, Wellesley College

Classification via effective lists

'Classifying' a natural collection of structures is a common goal in mathematics. Providing a classification can mean different things, e.g., identifying a set of invariants that settle the isomorphism problem or creating a list of all structures of a given kind without repetition of isomorphism type. Here we discuss recent work on classifications of the latter kind from the perspective of computable structure theory. We’ll consider natural classes of computable structures such as vector spaces, equivalence relations, algebraic fields, and trees to better understand the nuances of classification via effective lists and its relationship to other forms of classification in this setting.



- - - - Other Logic News - - - -

CONFERENCE ANNOUNCEMENT
Saul Kripke Memorial Conference
May 8-9, 2023
The Saul Kripke Center and CUNY Graduate Center

The Saul Kripke Center will host a memorial conference honoring Saul Kripke (1940-2022) at The CUNY Graduate Center on May 8th and 9th, 2023. The conference program is available here. Registration for attending in person is not required, but attendees will have to comply with the Graduate Center’s Building Access Policy. Although the conference will be a mainly in person event, a livestream is also available; for this, please register.



- - - - Web Site - - - -

Find us on the web at:  nylogic.github.io
(site designed, built & maintained by Victoria Gitman)

--------  ADMINISTRIVIA  --------

To subscribe/unsubscribe to this list, please email your request to jreitz@citytech.cuny.edu.

If you have a logic-related event that you would like included in future mailings, please email jreitz@citytech.cuny.edu.

(KGRC) talks in the Set Theory Seminar on April 25 and April 27

Kurt Godel Research Center
The KGRC welcomes as guests: Clifton Ealy (host: Matthias Aschenbrenner) visits the KGRC until August 15. Sergei Starchenko (host: Matthias Aschenbrenner) visits the KGRC from April 16 to April 30 and gives a talk, details to be announced at a later time. Tomasz Żuchowski (host: Damian Sobota) visits the KGRC from April 24 to April 30 and gives a talk, see below. Heike Mildenberger (host: Vera Fischer) visits the KGRC from May 3 to May 6 and gives a talk on May 4, details to be announced at a later time. Fabian Kaak (host: Vera Fischer) visits the KGRC from May 23 to May 26 and gives a short talk, details to be announced at a later time. Jaroslav Šupina (host: Vera Fischer) visits the KGRC from June 18 to June 24 and gives a talk, details to be announced at a later time. Nadiya Kolos (host: Miguel Moreno) visits the KGRC from June 19 to June 23 and gives a talk, details to be announced at a later time. * * * Set Theory Seminar Kurt Gödel Research Center Tuesday, April 25 "Nonseparable growth of $\omega$ supporting a strictly positive measure" Tomasz Żuchowski (University of Wrocław, PL) During the talk I will present a construction in ZFC of a compactification of $\omega$ such that its remainder is not separable and carries a strictly positive measure, i.e. measure positive on nonempty open subsets. The measure is defined using the asymptotic density of subsets of $\omega$. The remainder is a Stone space of some Boolean subalgebra of Borel subsets of the Cantor space containing all clopen sets, constructed with an aid of an uncountable almost disjoint family of subsets of $\omega$. This is a joint work with Piotr Borodulin-Nadzieja. Time and Place Talk at 3:00pm in hybrid mode: on-site as well as via Zoom Universität Wien Institut für Mathematik Kolingasse 14-16 1090 Wien 1st floor Seminar room 10 Zoom: If you need the Zoom data and have not received the meeting link by the day before the talk, please contact richard.springer@univie.ac.at! Please direct any other questions about this talk to vera.fischer@univie.ac.at. * * * Set Theory Seminar Kurt Gödel Research Center Thursday, April 27 "Cardinalities of sets of reals satisfying combinatorial covering properties" Lyubomyr Zdomskyy (TU Wien) We shall discuss which cardinalities sets of reals satisfying Menger and Hurewicz covering properties may have in some standard models of ZFC. Most of the results may be thought of as consistent instances of the Perfect Set Property, since they state that in some models, a set of reals satisfying certain covering properties either contains a copy of the Cantor set, or has small size. In particular, we plan to outline the proof of the fact that in the Sacks model every Menger totally imperfect set of reals has size at most w_1. This is a joint work with V. Haberl and P. Szewczak. Time and Place Talk at 11:30am in hybrid mode: on-site as well as via Zoom Universität Wien Institut für Mathematik Kolingasse 14-16 1090 Wien 1st floor Seminar room 10 Zoom: If you need the Zoom data and have not received the meeting link by the day before the talk, please contact richard.springer@univie.ac.at! Please direct any other questions about this talk to vera.fischer@univie.ac.at.

Wednesday seminar -- joint seminar of the MLTCS department

Prague Set Theory Seminar
Dear all, The seminar next week will be held as a joint seminar of the MLTCS department. This means we expect a slightly wider audience and the plan is to go for a lunch after the seminar. Please do let me know if you intend to come so that we can make estimates for the table reservation. ***ROOM CHANGE*** The seminar will meet on Wednesday April 26th at 11:00 in the Institute of Mathematics CAS, blue lecture hall, ground floor, rear building, Zitna 25. Program: David Uhrik -- Colorings of Infinite Graphs We will give an overview of new results on uncountable graphs obtained in my phd thesis. Topics will range from Ramsey theory, the chromatic number to the uncountable Hadwiger conjecture. We studied various graph constructions in Cohen extensions. We showed that adding aleph-two Cohen reals forces a weak bipartite-type partition relation on aleph-two. From a single Cohen real we constructed a triangle free Hajnal--Máté graph, answering a question of Dániel Soukup. Using the same method a new construction of a T-Hajnal--Máté graph was provided in ZFC. We introduced so-called delta-Hajnal--Máté graphs and showed that they do not exist under Martin's axiom. Lastly in connection to the uncountable Hadwiger conjecture we proved that the least size of a counterexample to the uncountable Hadwiger conjecture is equal to the special tree number. Best, David

Charla de Andrés Uribe en el Seminario Colombo Mexicano de Teoría de Conjuntos

Seminario Colombo Mexicano de Teoría de Conjuntos

Seminario Colombo Mexicano de Teoría de Conjuntos

 

Abril 20

4:00 p.m. - 5:00 p.m. (hora de Colombia)  

 

FAM-ligadura: hacia una teoría general de forcing iterado usando medidas finitamente aditivas.
Andrés F. Uribe

Universidad Nacional de Colombia

 

Resumen. En el año 2000, Shelah logró demostrar que, consistentemente, el número de cubrimiento del ideal de los subconjuntos nulos de los números reales puede tener cofinalidad contable. Para ello, usando random forcing, construyó una iteración de soporte finito con medidas finitamente aditivas. En esta charla se va a presentar la definición de una nueva noción de ligadura, llamada FAM-ligadura, que permite generalizar la iteración que Shelah introdujo originalmente y definir una teoría general de forcing iterado usando medidas finitamente aditivas. Además, se va a exponer una nueva constelación del digrama de Cichoń donde se separa el lado izquierdo, y el número de cubrimiento del ideal de los subconjuntos nulos de los números reales es singular.


Zoom meeting information.
Meeting ID: 856 1882 0721
Passcode: 123456

Cross-Alps Logic Seminar (speaker: Márton Elekes)

Cross-Alps Logic Seminar
On Friday 21.04.2023 at 16.00
Márton Elekes (Rényi Institute and Eötvös Loránd University)
will give a talk on 
On various notions of universally Baire sets

Please refer to the usual webpage of our LogicGroup for more details and the abstract of the talk.
The seminar will be held remotely through Webex. Please write to vincenzo.dimonte [at] uniud [dot] it for the link to the event.

The Cross-Alps Logic Seminar is co-organized by the logic groups of Genoa, Lausanne, Turin and Udine as part of our collaboration in the project PRIN 2017 'Mathematical logic: models, sets, computability'.

All the best,
Vincenzo

Nankai Logic Colloquium

Nankai Logic Colloquium

Hello everyone,

This week our weekly Nankai Logic Colloquium is going to be in the afternoon.

Our speaker this week will be Raphael Carroy from the University of Turin. This talk is going to take place this Friday, Apr. 21,  from 4pm to 5pm (UTC+8, Beijing time). 

Title: Continuous reducibility is a well-quasi-order on continuous functions with Polish 0-dimensional domains.

Abstract: Given topological spaces $X,X',Y,Y'$, and two functions $f:X\to Y$ and $f':X'\to Y'$, we say that $f$ \emph{reduces continuously} to $f'$ when there is a pair $(\sigma,\tau)$ of continuous functions such that $f=\tau\circ f'\circ\sigma$. This quasi-order has first been introduced by Weihrauch in the context of Computable Analysis at the beginning of the 1990s. It has recently received interest in Descriptive Set Theory.
With Yann Pequignot, we proved that on the class of continuous functions with Polish 0-dimensional domains, there are no infinite antichains and no infinite strictly descending chains for continuous reducibility. In other words, continuous reducibility is a well-quasi-order on this class of functions.
I will give some context for this result and outline the proof.


_________________________________________________________
Title : The 25th Nankai Logic Colloquium --Raphael Carroy
Time :16:00pm, Apr. 21, 2023 (Beijing Time) 
Zoom Number : 812 8606 8722
Passcode : 165561
Link : https://us02web.zoom.us/j/81286068722?pwd=V3V3NUpKNFgxQldLdEF1TW56WTNXQT09

_____________________________________________________________________


Best wishes,

Ming Xiao




This Week in Logic at CUNY

This Week in Logic at CUNY
This Week in Logic at CUNY:

- - - - Monday, Apr 17, 2023 - - - -

Rutgers Logic Seminar 
Monday, April 17, 2pm, Rutgers University, Hill 005
Alejandro Poveda, CMSA Harvard
The Gluing Property


Logic and Metaphysics Workshop
Date: Monday, April 17, 4.15-6.15pm (NY time), GC 9206
NOTE: Meetings this semester are in person only (no zoom)
For meeting information, please sign up for our mailing list at https://logic.commons.gc.cuny.edu/about/
Branden Fitelson (Northeastern).
Title: Probability and logic/meaning: Two approaches

Abstract: In this talk, I will compare and contrast two approaches to the relation between probability and logic/meaning.  First, I will examine the Traditional (“Kolmogorovian”) Approach of setting up probability calculi, which presupposes semantic/logical notions and defines conditional probability in terms of unconditional probability.  Then, I will discuss the Popperian Approach, which does not presuppose semantic/logical notions, and which takes conditional probability as primitive.  Along the way, I will also discuss the prospects (and pitfalls) of adding an Adams-style conditional to various probability calculi.




- - - - Tuesday, Apr 18, 2023 - - - -

Models of Peano Arithmetic (MOPA)
Tuesday, April 18, 1:00pm
Virtual (email Victoria Gitman vgitman@gmail.com for meeting id)

Katarzyna W. Kowalik, University of Warsaw
The chain-antichain principle and proof size

The chain-antichain principle  is a well-known consequence of Ramsey's theorem for pairs and two colours . It says that for every partial order on  there exists an infinite chain or antichain with respect to this order. Both of these principles are -conservative over the weak base theory . Such conservation results usually prompt to ask about lengths of proofs. Kołodziejczyk, Wong and Yokoyama proved that  has a non-elementary speedup over  for proofs of  sentences. We show that the behaviour of  is the opposite: it can be polynomially simulated by  with respect to  sentences. Our argument uses a technique of forcing interpretation developed by Avigad. In the first step we syntactically simulate a construction of a generic computable ultrapower of a model of . Then we find a generic cut satisfying  inside the ultrapower.




- - - - Wednesday, Apr 19, 2023 - - - -

The New York City Category Theory Seminar
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York

Speaker:     Walter Tholen, York University.

Date and Time:     Wednesday April 19, 2023, 7:00 - 8:30 PM. ZOOM TALK.

Title:     What does “smallness” mean in categories of topological spaces?


Abstract: Quillen’s notion of small object and the Gabriel-Ulmer notion of finitely presentable or generated object are fundamental in homotopy theory and categorical algebra. Do these notions always lead to rather uninteresting classes of objects in categories of topological spaces, such as the class of finite discrete spaces, or just the empty space , as the examples and remarks in the existing literature may suggest?

In this talk we will demonstrate that the establishment of full characterizations of these notions (and some natural variations thereof) in many familiar categories of spaces, such as those of T_i-spaces (i= 0, 1, 2), can be quite challenging and may lead to unexpected surprises. In fact, we will show that there are significant differences in this regard even amongst the categories defined by the standard separation conditions, with the T1-separation condition standing out. The findings about these specific categories lead us to insights also when considering rather arbitrary full reflective subcategories of Top.

(Based on joint work with J. Adamek, M. Husek, and J. Rosicky.)



- - - - Thursday, Apr 20, 2023 - - - -



- - - - Friday, Apr 21, 2023 - - - -

Set Theory Seminar
CUNY Graduate Center
Friday, April 21, 12:15pm NY time
Virtual: Please email Victoria Gitman (vgitman@gmail.com) for meeting id.
Mohammad Golshani, Institute for Research in Fundamental Sciences

The proper forcing axiom for -sized posets and the continuum

We discuss Shelah's memory iteration technique and use it to show that the PFA for posets of size  is consistent with large continuum. This is joint work with David Aspero.




Logic Workshop
CUNY Graduate Center
Friday April 21, 2:00pm-3:30pm, Room 6417
James Hanson, University of Maryland

How bad could it be? The semilattice of definable sets in continuous logic

Continuous first-order logic is a generalization of discrete first-order logic suited for studying structures with natural underlying metrics, such as operator algebras and -trees. While many things from discrete model theory generalize directly to continuous model theory, there are also new subtleties, such as the correct notion of 'definability' for subsets of a structure. Definable sets are conventionally taken to be those that admit relative quantification in an appropriate sense. An easy argument then establishes that the union of definable sets is definable, but in general the intersection of definable sets may fail to be. This raises the question of which semilattices arise as the partial order of definable sets in a continuous theory.

After giving an overview of the basic properties of definable sets in continuous logic, we will give a largely visual proof that any finite semilattice (and therefore any finite lattice) is the partial order of definable sets in some superstable continuous first-order theory. We will then discuss a partial extension of this to certain infinite semilattices.




Next Week in Logic at CUNY:

- - - - Monday, Apr 24, 2023 - - - -

Rutgers Logic Seminar 
Monday, April 24, 2pm, Rutgers University, Hill 005
Aristotelis Panagiotopoulos, CMU


Logic and Metaphysics Workshop
Date: Monday, April 24, 4.15-6.15pm (NY time), GC 9206
NOTE: Meetings this semester are in person only (no zoom)
For meeting information, please sign up for our mailing list at https://logic.commons.gc.cuny.edu/about/
Andrea Iacona (Turin).
Title: Inferentialism and connexivity

Abstract: In my talk I will investigate the relationships between two claims about conditionals that by and large are discussed separately. One is the claim that a conditional holds when its consequent can be inferred from its antecedent, or when the latter provides a reason for accepting the former. The other is the claim that conditionals intuitively obey some characteristic connexive principles, such as Aristotle’s Thesis and Boethius Thesis. Following a line of thought that goes back to Chrysippus, I will suggest that these two claims may coherently be understood as distinct manifestations of a single basic idea, namely, that a conditional holds when its antecedent is incompatible with the negation of its consequent. The account of conditionals that I will outline is based precisely on this idea.



- - - - Tuesday, Apr 25, 2023 - - - -

Models of Peano Arithmetic (MOPA)
Tuesday, April 25, 1:00pm
Virtual (email Victoria Gitman vgitman@gmail.com for meeting id)
Mateusz Łełyk University of Warsaw



- - - - Wednesday, Apr 26, 2023 - - - -

The New York City Category Theory Seminar
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York

Speaker:     Dusko Pavlovic, University of Hawai‘i at Mānoa.

Date and Time:     Wednesday April 26, 2023, 7:00 - 8:30 PM. ZOOM TALK.

Title:     Program-closed categories.


Abstract: > Let CC be a symmetric monoidal category with a comonoid on every object. Let CC* be the cartesian subcategory with the same objects and just the comonoid homomorphisms. A *programming language* is a well-ordered object P with a *program closure*: a family of X-natural surjections
CC(XA,B) <<--run_X-- CC*(X,P)
one for every pair A,B. In this talk, I will sketch a proof that program closure is a property: Any two programming languages are isomorphic along run-preserving morphisms. The result counters Kleene's interpretation of the Church-Turing Thesis, which has been formalized categorically as the suggestion that computability is a structure, like a group presentation, and not a property, like completeness. We prove that it is like completeness. The draft of a book on categorical computability is available from the web site dusko.org.




- - - - Thursday, Apr 27, 2023 - - - -



- - - - Friday, Apr 28, 2023 - - - -

Set Theory Seminar
CUNY Graduate Center
Friday, April 28, 12:15pm NY time
Virtual: Please email Victoria Gitman (vgitman@gmail.com) for meeting id.
Will Boney Texas State University


- - - - Other Logic News - - - -


- - - - Web Site - - - -

Find us on the web at:  nylogic.github.io
(site designed, built & maintained by Victoria Gitman)

--------  ADMINISTRIVIA  --------

To subscribe/unsubscribe to this list, please email your request to jreitz@citytech.cuny.edu.

If you have a logic-related event that you would like included in future mailings, please email jreitz@citytech.cuny.edu.

Wednesday seminar

Prague Set Theory Seminar
Dear all, The seminar meets on Wednesday April 19th at 11:00 in the Institute of Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building. The program is not yet fixed, the preliminary plan is to look at some classical forcing results to broaden/refresh our education in the subject. Best, David

(KGRC) two talks on Thursday, April 20

Kurt Godel Research Center
The KGRC welcomes as guests: Clifton Ealy (host: Matthias Aschenbrenner) visits the KGRC until August 15. Sergei Starchenko (host: Matthias Aschenbrenner) visits the KGRC from April 16 to April 30 and gives a talk, details to be announced at a later time. Zoltán Vidnyánszky (host: Vera Fischer) visits the KGRC on April 20 and gives a talk, see below. Heike Mildenberger (host: Vera Fischer) visits the KGRC from May 3 to May 6 and gives a talk on May 4, details to be announced at a later time. Fabian Kaak (host: Vera Fischer) visits the KGRC from May 23 to May 26 and gives a short talk, details to be announced at a later time. Jaroslav Šupina (host: Vera Fischer) visits the KGRC from June 18 to June 24 and gives a talk, details to be announced at a later time. Nadiya Kolos (host: Miguel Moreno) visits the KGRC from June 19 to June 23 and gives a talk, details to be announced at a later time. * * * For a video recording of Martin Pinsker's talk, please see his slides at https://dmg.tuwien.ac.at/pinsker/talks/2023/pinsker_KGRC.pdf and a video recording at https://univienna.zoom.us/rec/share/rKNNyLly9EuERJbt_r2qp-71ktMjeAR5i5zFIq7HhA0g57kgC_T9tZs4VjMFJc85.fFpWWl1LZ8WHgVGg (use passcode ?yG874^^ to watch) * * * Set Theory Seminar Kurt Gödel Research Center Thursday, April 20 (Please note the unuasual day and time: Starting in April, most of the talks in the Set Theory Seminar will be moved to Thursday, 11:30am. A few will remain on Tuesday, 3:00pm however.) "Menger spaces everywhere" Lyubomyr Zdomskyy (TU Wien) Combinatorial covering properties, which arose from the study of classical special sets of reals, appear in many contexts in topology and set theory. In this talk we shall discuss some applications of the Menger property and certain stronger versions thereof. It is planned to be a gentle introduction to the next talk on April 27. Time and Place Talk at 11:30am in hybrid mode: on-site as well as via Zoom Universität Wien Institut für Mathematik Kolingasse 14-16 1090 Wien 1st floor Seminar room 10 Zoom: If you need the Zoom data and have not received the meeting link by the day before the talk, please contact richard.springer@univie.ac.at! Please direct any other questions about this talk and the Zoom session to vera.fischer@univie.ac.at. * * * Logic Colloquium Kurt Gödel Research Center Tuesday, April 20 "Homomorphism problems in the infinite context" Zoltán Vidnyánszky (Eötvös Loránd U, HU) The CSP dichotomy of Bulatov and Zhuk is a celebrated theorem of computer science: it states that given a finite structure H, deciding whether a structure G admits a homomorphism to G is either easy (in P) or hard (NP-complete). We will discuss two infinitary versions of this theorem. First, following Thornton, in the Borel con ext. Here a striking difference from the finite world emerges: we will show that solving linear equations over a finite field is already hard ($\Sigma^1_2$-complete). Second, assuming only ZF, we will consider the relationship of the H-compactness properties, that is, the statement that for every G if every finite substructure of G admits a homomorphism to H then so is G. Here we show that there exists a model M of ZF, such that M $\models$ H-compactness iff the H-homomorphism problem is easy. Time and Place Talk at 3:00pm in hybrid mode: on-site as well as via Zoom Universität Wien Institut für Mathematik Oskar-Morgenstern-Platz 1 1090 Wien 2nd floor room HS 11 Zoom: If you need the Zoom data and have not received the meeting link by the day before the talk, please contact richard.springer@univie.ac.at! Please direct any other questions about this talk and the Zoom session to vera.fischer@univie.ac.at.

Fwd: Announcement - PhDs in Logic

Barcelona Logic Seminar

Dear colleagues, 

                                                                            We would like to announce the XIV edition of the conference PhDs in Logic 2023 that will take place in Granada, Spain, 4-6 october.
                                     
                                                    
There will be 6 keynote talks primarily aimed at PhD students and early career researchers.

Keynote speakers:
  • Tomás Ibarlucía - Université de Paris
  • Jordi López Abad - UNED
  • Nina Gierasimczuk - Danish Technical University
  • Amanda Vidal - IIIA - CSIC
  • Julian Murzy - University of Salzburg
  • María José Frápolli Sanz - Universidad de Granada

----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------


All participants are encouraged to submit an abstract (1000 words). In case it is accepted, the scientific committee will then decide if the abstract merits a 20 minutes presentation and the poster session, or just the poster session. 



----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------



Student members of the Association for Symbolic Logic (ASL) may apply for travel support at ASL. Note that such applications have to be submitted at least 3 months prior to the meeting.

The "Sociedad de Lógica, Metodología y Filosofía de la Ciencia" also offers support for members. https://solofici.org/ayudas-a-jovenes-investigadores-para-la-asistencia-a-congresos-internacionales-2/



----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------



See the webpage of the meeting for further information https://phdsinlogicxiv.com/ and do not hesitate to contact us at phdsinlogic@gmail.com.



Best,
Catalina Torres
Jose Santiago
Daira Pinto
Juan M Santiago

Joan Bagaria 
ICREA Research Professor 
Universitat de Barcelona
Departament de Matemàtiques i Informàtica
Gran Via de les Corts Catalanes 585
08007 Barcelona
Catalonia 

Phone: +34 93 402 1609
joan.bagaria@icrea.cat
bagaria@ub.edu


Charla de Luis Reyes en el Seminario Colombo Mexicano de Teoría de Conjuntos

Seminario Colombo Mexicano de Teoría de Conjuntos

Seminario Colombo Mexicano de Teoría de Conjuntos

 

Abril 13

4:00 p.m. - 5:00 p.m. (hora de Colombia)  

 

Espacios de Johnson-Lindenstrauss y familias AD
Luis D. Reyes

Universidad Nacional Autónoma de México

 

Resumen. Los espacios de Johnson-Lindentrauss fueron introducidos por ambos autores en los años setentas como un contraejemplo 'artificial' a propiedades topológicas en análisis funcional. Sin embargo, el estudio de estos espacios ha llevado a entenderlos a través de familias casi ajenas (AD) y las compactaciones de su psi-espacio.

En esta charla, daremos un breve repaso de algunos resultados en esta línea de investigación, así como una introducción a los métodos que permiten traducir propiedades combinatorias de las familias AD a importantes propiedades topológicas de los espacios de Banach.


Zoom meeting information.
Meeting ID: 856 1882 0721
Passcode: 123456

Logic Seminar 12 April 2023 17:00 hrs at NUS by Daniel Hoffmann via Zoom

NUS Logic Seminar
Hello, here is some local talk at 16:00 hrs in which some of the local people might be interested. In order to avoid a clash, we start this talk at 17:15 hrs. Chieu Minh, please inform Daniel. Regards, Frank On Mon, Apr 10, 2023 at 04:05:19PM +0800, Frank STEPHAN wrote: > Invitation to the Logic Seminar at the National University of Singapore > > Date: Wednesday, 12 April 2023, 17:00 hrs > > Place: Talk via Zoom: > https://nus-sg.zoom.us/j/83049258042?pwd=UWViaWNvTFUrdFdhOHJCdEVydnVkdz09 > Meeting ID: 830 4925 8042 > Passcode: 1729=x3+y3 > > Speaker: Daniel Hoffmann > > Title: Model completeness of SL(2,R) > > URL: http://www.comp.nus.edu.sg/~fstephan/logicseminar.html > > I will present some results from my joint project with Chieu Minh > Tran and Jinhe Ye. Model completeness is a weakening of quantifier > elimination. The main task here is to define a field in the structure > of the pure group, but in such a way that this definition transfers > over some group extensions. I will recall basic facts from the model > theory needed here and similar recent results in the field, then - > hopefully - I will be able to sketch the idea of the proof, which is > quite geometric. >

This Week in Logic at CUNY

This Week in Logic at CUNY
This Week in Logic at CUNY:

- - - - Monday, Apr 10, 2023 - - - -

Rutgers Logic Seminar - TODAY'S SEMINAR CANCELLED

*** April 5-13, 2023 Spring Recess CUNY Graduate Center ***


- - - - Tuesday, Apr 11, 2023 - - - -

*** April 5-13, 2023 Spring Recess CUNY Graduate Center ***


- - - - Wednesday, Apr 12, 2023 - - - -

*** April 5-13, 2023 Spring Recess CUNY Graduate Center ***


- - - - Thursday, Apr 13, 2023 - - - -

*** April 5-13, 2023 Spring Recess CUNY Graduate Center ***



- - - - Friday, Apr 14, 2023 - - - -

Set Theory Seminar
CUNY Graduate Center
Friday, April 14, 12:15pm NY time
Virtual: Please email Victoria Gitman (vgitman@gmail.com) for meeting id.
Gabriel Goldberg, University of California, Berkeley
TBA



Next Week in Logic at CUNY:

- - - - Monday, Apr 17, 2023 - - - -

Rutgers Logic Seminar 
Monday, April 17, 2pm, Rutgers University, Hill 005
Alejandro Poveda, CMSA Harvard



Logic and Metaphysics Workshop
Date: Monday, April 17, 4.15-6.15pm (NY time), GC 9206
NOTE: Meetings this semester are in person only (no zoom)
For meeting information, please sign up for our mailing list at https://logic.commons.gc.cuny.edu/about/
Branden Fitelson (Northeastern).
Title: Probability and logic/meaning: Two approaches

Abstract: In this talk, I will compare and contrast two approaches to the relation between probability and logic/meaning.  First, I will examine the Traditional (“Kolmogorovian”) Approach of setting up probability calculi, which presupposes semantic/logical notions and defines conditional probability in terms of unconditional probability.  Then, I will discuss the Popperian Approach, which does not presuppose semantic/logical notions, and which takes conditional probability as primitive.  Along the way, I will also discuss the prospects (and pitfalls) of adding an Adams-style conditional to various probability calculi.




- - - - Tuesday, Apr 18, 2023 - - - -

Models of Peano Arithmetic (MOPA)
Tuesday, April 18, 1:00pm
Virtual (email Victoria Gitman vgitman@gmail.com for meeting id)
Katarzyna W. Kowalik, University of Warsaw


- - - - Wednesday, Apr 19, 2023 - - - -

The New York City Category Theory Seminar
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York

Speaker:     Walter Tholen, York University.

Date and Time:     Wednesday April 19, 2023, 7:00 - 8:30 PM. ZOOM TALK.

Title:     What does “smallness” mean in categories of topological spaces?


Abstract: Quillen’s notion of small object and the Gabriel-Ulmer notion of finitely presentable or generated object are fundamental in homotopy theory and categorical algebra. Do these notions always lead to rather uninteresting classes of objects in categories of topological spaces, such as the class of finite discrete spaces, or just the empty space , as the examples and remarks in the existing literature may suggest?

In this talk we will demonstrate that the establishment of full characterizations of these notions (and some natural variations thereof) in many familiar categories of spaces, such as those of T_i-spaces (i= 0, 1, 2), can be quite challenging and may lead to unexpected surprises. In fact, we will show that there are significant differences in this regard even amongst the categories defined by the standard separation conditions, with the T1-separation condition standing out. The findings about these specific categories lead us to insights also when considering rather arbitrary full reflective subcategories of Top.

(Based on joint work with J. Adamek, M. Husek, and J. Rosicky.)



- - - - Thursday, Apr 20, 2023 - - - -



- - - - Friday, Apr 21, 2023 - - - -

Set Theory Seminar
CUNY Graduate Center
Friday, April 14, 12:15pm NY time
Virtual: Please email Victoria Gitman (vgitman@gmail.com) for meeting id.
Mohammad Golshani, Institute for Research in Fundamental Sciences
TBA


Logic Workshop
CUNY Graduate Center
Friday April 21, 2:00pm-3:30pm, Room 6417
James Hanson, University of Maryland
TBA


- - - - Other Logic News - - - -


- - - - Web Site - - - -

Find us on the web at:  nylogic.github.io
(site designed, built & maintained by Victoria Gitman)

--------  ADMINISTRIVIA  --------

To subscribe/unsubscribe to this list, please email your request to jreitz@citytech.cuny.edu.

If you have a logic-related event that you would like included in future mailings, please email jreitz@citytech.cuny.edu.

Nankai Logic Colloquium

Nankai Logic Colloquium

Hello everyone,

This week our weekly Nankai Logic Colloquium is going to be in the morning.

Our speaker this week will be Chris Laskowski from the University of Maryland. This talk is going to take place this Friday, Apr. 14,  from 9am to 10am(UTC+8, Beijing time). 


Title:  On the Borel complexity of modules

Abstract:  We prove that among all countable, commutative rings R (with unit) the theory of R-modules is not Borel complete if and only if there are only countably many non-isomorphic countable R-modules.  From the proof, we obtain a succinct proof that the class of torsion free abelian groups is Borel complete.
   The results above follow from some general machinery that we expect to have applications in other algebraic settings.  Here, we also show that for an arbitrary countable ring R, the class of left R-modules equipped with an endomorphism is Borel complete; as is the class of left R-modules equipped with predicates for four submodules.  This is joint work with Danielle Ulrich.



_________________________________________________________

Title : The 24th Nankai Logic Colloquium --Chris Laskowski
Time : 9:00am, Apr. 14, 2023 (Beijing Time) 
Zoom Number : 836 6352 7223
Passcode : 673161

_____________________________________________________________________


Best wishes,

Ming Xiao




Logic Seminar 12 April 2023 17:00 hrs at NUS by Daniel Hoffmann via Zoom

NUS Logic Seminar
Invitation to the Logic Seminar at the National University of Singapore Date: Wednesday, 12 April 2023, 17:00 hrs Place: Talk via Zoom: https://nus-sg.zoom.us/j/83049258042?pwd=UWViaWNvTFUrdFdhOHJCdEVydnVkdz09 Meeting ID: 830 4925 8042 Passcode: 1729=x3+y3 Speaker: Daniel Hoffmann Title: Model completeness of SL(2,R) URL: http://www.comp.nus.edu.sg/~fstephan/logicseminar.html I will present some results from my joint project with Chieu Minh Tran and Jinhe Ye. Model completeness is a weakening of quantifier elimination. The main task here is to define a field in the structure of the pure group, but in such a way that this definition transfers over some group extensions. I will recall basic facts from the model theory needed here and similar recent results in the field, then - hopefully - I will be able to sketch the idea of the proof, which is quite geometric.

Wednesday seminar

Prague Set Theory Seminar
Dear all, The seminar meets on Wednesday April 12th at 11:00 in the Institute of Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building. Program: Martin Balko -- On ordered Ramsey numbers The ordered Ramsey number of an ordered graph G^< (that is, graph with a fixed linear ordering of its vertices) is the smallest positive integer N such that every 2-coloring of the edges of ordered K^

Nankai Logic Colloquium

Nankai Logic Colloquium

Hello everyone,


This week our weekly Nankai Logic Colloquium is going to be in the afternoon.


Our speaker this week will be David Schritesser from Harbin Institute of Technology. This talk is going to take place this Friday,  Apr 07 ,  from 4pm to 5pm(UTC+8, Beijing time). 

Title: Definability of Maximal Cofinitary Groups

Abstract: The notion of a cofinitary groups was named by Peter Cameron in the 1980ies, as a dual to the notion of finitary permutation groups. Cameron asked about such groups which are maximal in the sense that they are not proper subgroups of another cofinitary group. It was long thought that such maximal cofinitary groups are necessarily extremely complicated objects.

In 2016, Horowitz and Shelah showed that there is a Borel maximal cofinitary group. I recent joint work with my student Severin Mejak, that there is even an F_sigma such group, which is isomorphic to a free group. Among free maximal cofinitary groups, this is the lowest possible complexity. In this talk, I will give some ideas of the proof.

___________________________________________________________________________________________________________________________________________________


This is going to be an online event. Follow the link below to join the Zoom meeting. Please use your real name to join the meeting.

Title : The 23rd Nankai Logic Colloquium --David Schrittesser

Time : 16:00pm, Apr. 07, 2023 (Beijing Time) 

Zoom Number : 867 3454 6492

Passcode : 766848

_____________________________________________________________________


Best wishes,

Ming Xiao




This Week in Logic at CUNY

This Week in Logic at CUNY
This Week in Logic at CUNY:

- - - - Monday, Apr 3, 2023 - - - -

Logic and Metaphysics Workshop
Date: Monday, April 3, 4.15-6.15pm (NY time), GC 9206
NOTE: Meetings this semester are in person only (no zoom)
For meeting information, please sign up for our mailing list at https://logic.commons.gc.cuny.edu/about/

Thomas Ferguson (Czech Academy of Sciences).
Title: Care-theoretic semantics: Problems and non-deterministic solutions

Abstract: In this talk I will present the details of a project of care-theoretic semantics in which a linguistic feature of care–rather than truth–is understood as the fundamental semantic property. I will review the details, including how adopting a bounds consequence position in which bounds are determined by considerations of topic allows one to determine both a theory of inference and theory of meaning on the basis of care alone. I will consider two challenges to the project: that of the reconciliation of topic-theoretic and truth-theoretic bounds (in which we need to acknowledge cases in which a position crosses both types of bounds) and sui generis monstrous content (in which two anodyne sentences together yield a content-theoretic violation). I will show that in both cases intuitions suggest the use of Nmatrices in the style of Avron and consider the merits of their employment in the care-theoretic setting.



- - - - Tuesday, Apr 4, 2023 - - - -



- - - - Wednesday, Apr 5, 2023 - - - -

*** April 5-13, 2023 Spring Recess CUNY Graduate Center ***


- - - - Thursday, Apr 6, 2023 - - - -



- - - - Friday, Apr 7, 2023 - - - -

Set Theory Seminar
CUNY Graduate Center
Friday, April 7, 12:15pm NY time
Virtual: Please email Victoria Gitman (vgitman@gmail.com) for meeting id.
Miha Habič, Bard College at Simon's Rock

Some old and new results on nonamalgamable forcing extensions

Fixing some countable transitive model  of set theory, we can consider its generic multiverse, the family of all models obtainable from  by taking any sequence of forcing extensions and ground models. There is an attractive similarity between the generic multiverse and the Turing degrees, but the multiverse has the drawback (or feature?) that it contains nonamalgamable models, that is, models with no common upper bound, as was observed by several people, going back to at least Mostowski. In joint work with Hamkins, Klausner, Verner, and Williams in 2019, we studied the order-theoretic properties of the generic multiverse and, among other results, gave a characterization of which partial orders embed nicely into the multiverse. I will present our results in the simplest case of Cohen forcing, as well as existing generalizations to wide forcing, and some new results on non-Cohen ccc forcings.



*** April 5-13, 2023 Spring Recess CUNY Graduate Center ***


Next Week in Logic at CUNY:

- - - - Monday, Apr 10, 2023 - - - -

Rutgers Logic Seminar
Monday, April 10, 2pm, Rutgers University, Hill 005
Victoria Gitman, CUNY
Jensen's forcing at an inaccessible


- - - - Tuesday, Apr 11, 2023 - - - -



- - - - Wednesday, Apr 12, 2023 - - - -



- - - - Thursday, Apr 13, 2023 - - - -

*** April 5-13, 2023 Spring Recess CUNY Graduate Center ***



- - - - Friday, Apr 14, 2023 - - - -



- - - - Other Logic News - - - -


- - - - Web Site - - - -

Find us on the web at:  nylogic.github.io
(site designed, built & maintained by Victoria Gitman)

--------  ADMINISTRIVIA  --------

To subscribe/unsubscribe to this list, please email your request to Jonas.Reitz12@citytech.cuny.edu.

If you have a logic-related event that you would like included in future mailings, please email Jonas.Reitz12@citytech.cuny.edu.

Wednesday seminar

Prague Set Theory Seminar
Dear all, The seminar meets on Wednesday April 5th at 11:00 in the Institute of Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building. Program: Jonathan Cancino Manriquez -- On AD families of subsets of the rational numbers We will talk about some basic properties of almost disjoint families modulo the ideal of nowhere dense sets. Best, David

Logic Seminar 5 April 2023 17:00 hrs at NUS by Frank Stephan

NUS Logic Seminar
Invitation to the Logic Seminar at the National University of Singapore Date: Wednesday, 5 April 2023, 17:00 hrs Place: NUS, Department of Mathematics, S17#05-11 Speaker: Frank Stephan Title: Languages given by finite automata over the unary alphabet URL: http://www.comp.nus.edu.sg/~fstephan/logicseminar.html Languages over the unary alphabet have been studied in computer science for a long time. The present work investigates regular languages over the unary alphabet and one investigates the various forms of representing them by finite automata. Here three types of automata are studied: (a) Deterministic finite automata where the finite automaton has exactly one run per word which is accepting iff the word is in the given language. (b) Nondeterministic finite automata where there are choices in the states on how to procede with a run on various symbols, a word is in the language iff there is some run which is accepting. (c) Unambiguous finite automata which are a special case of nondeterministic finite automata and which either reject a word or which have exactly one accepting run for a word. The results presented are from the following two areas: (1) This paper improves the upper bound of the equality problem of unary nondeterministic automata from an exponential in the second root to an exponential in the third root of the number of states. This almost matches a known lower bound based on the exponential time hypothesis by Fernau and Krebs. (2) It is established that the standard regular operations of union, intersection, complementation and Kleene star cause either only a polynomial or a quasipolynomial blow-up. Concatenation of two n-state ufas, in worst case, causes a blow-up from n to a function with an exponent of sixth root of n. Decision problems of finite formulas using regular operations and comparing languages given by n-state unambiguous automata, in worst case, require an exponential-type of time under the Exponential Time hypothesis and this complexity goes down to quasipolynomial time in the case that the concatenation of languages is not used in the formula. Merely comparing two languages given by n-state ufas in Chrobak Normal Form is in LOGSPACE. This talk is joint work with Gordon Hoi, Sanjay Jain and Christopher Tan.

Core Model Seminar next Tuesday

Carnegie Mellon Logic Seminar
TUESDAY, April 4, 2023

Core Model Seminar:  1:30 - 3 PM Eastern, Online, Martin Zeman, University of California, Irvine

Join Zoom Meeting: https://cmu.zoom.us/j/97749733438?pwd=Yk5PcSsvekptWWxMNUhCU2pFbzA0Zz09
Meeting ID: 977 4973 3438
Passcode: 457791

TITLE: Distributivity of iterated club shooting and fine structural
models, part 1

ABSTRACT: Iterative adding closed unbounded sets through stationary sets found quite a few applications in set theory. One natural way to do this is adding club sets using posets consisting of initial segments of the desired clubs. In such situations, one important property of such iterations is sufficient amount of distributivity. In fact, establishing distributivity is often the main part of arguments that involve iterated club shooting.

There are two possible situations where one iteratively adds clubs.
First, for a fixed cardinal $\kappa$, one iteratively adds club subsets
of $\kappa^+$. This kind of construction proved to have many applications. Second, one may start with a cardinal $\delta$ and
iteratively add club subsets of cardinals $\kappa^+$ where $\kappa$
ranges over some set above $\delta$. Surprisingly, this kind of construction has not been much studied. In this talk we will focus on this situation.

In order to add a club subset of some stationary set $S$ the set $S$
must be large in a certain sense; such sets are called fat. It is known
that, consistently, iteratively adding club subsets of fat stationary sets
of $\omega_n$ on a tail-end of $n\in\omega$ followed by forming an
inverse limit at the end may collapse $\aleph_n$ to $\omega$. A strong form of fatness is the property of being the complement of a
non-reflecting stationary set. One can prove, using a fairly standard
argument, that if the iteration described above uses complements of
non-reflecting stationary sets instead of just fat sets, then such an
iteration is $(\omega_{n+1},\infty)$-distributive where $\omega_n$ is
the first active step in the iteration. One can also prove in ZFC that
the analogous  amount of distributivity holds of longer iterations,
where the first active step is at $\delta$ and inverse limits are used
at singular steps, as long as the singular steps are of cofinality
$<\delta$. Passing through singular steps of cofinality $\ge\delta$
seems to be difficult, and we only know how to do this over a fine
structural model where the non-reflecting stationary sets are carefully
chosen. Even in such a seemingly special case, the method does have applications.

This is a part of a joint work of Foreman-Magidor-Zeman on games with filters.

Charla de Daniel Calderón en el Seminario Colombo Mexicano de Teoría de Conjuntos

Seminario Colombo Mexicano de Teoría de Conjuntos

Seminario Colombo Mexicano de Teoría de Conjuntos

 

Marzo 30

4:00 p.m. - 5:00 p.m. (hora de Colombia)  

 

La conjetura de Borel y conjuntos magro-aditivos
Daniel Calderón

Universidad de Toronto

 

Resumen. Los conjuntos fuertemente nulos fueron introducidos por Borel y han sido estudiados desde comienzos del siglo pasado. Borel conjeturó que todo conjunto fuertemente nulo de reales debe ser contable. Algunos años más tarde, Sierpiński demostró que asumiendo CH existe un conjunto fuertemente nulo no contable. Sin embargo, la pregunta por la consistencia relativa a ZFC de la conjetura de Borel siguió irresoluta hasta que en 1976 Laver construyó, en un trabajo innovador, un modelo de ZFC en el que todo conjunto fuertemente nulo de reales es contable.

Un resultado debido a Galvin, Mycielski y Solovay, provee una caracterización de nulidad fuerte en términos de una propiedad algebraica para subconjuntos de la recta real. Utilizando esta caracterización, la noción de magro-aditividad apareció en escena. La magro-aditividad, al igual que otras nociones de pequeñes en la recta real, han recibido especial atención en años recientes. Una pregunta de 1993, debida a Bartoszyński y Judah, cuestiona si los conjuntos fuertemente nulos y los conjuntos magro-aditivos tienen una muy rígida relación en el sentido siguiente:
Pregunta (Bartoszyński–Judah, 1993): ¿Si todo subconjunto fuertemente nulo de la recta real es magro-aditivo, necesariamente vale la conjetura de Borel? 
En esta charla daré algunos detalles sobre la consistencia relativa de una respuesta negativa a la pregunta de Bartoszyński y Judah, construyendo un modelo de ZFC en el que todo conjunto fuertemente nulo de reales es magro-aditivo y la conjetura de Borel falla.


Zoom meeting information.
Meeting ID: 856 1882 0721
Passcode: 123456

Nankai Logic Colloquium

Nankai Logic Colloquium

Hello everyone,


This week our weekly Nankai Logic Colloquium is going to be in the afternoon.


Our speaker this week will be Samuel Coskey from Boise State University. This talk is going to take place this Friday, Mar 31,  from 16:00 to 17:00(UTC+8, Beijing time). 

Title: Borel classification of conjugacy problems

Abstract: We aim to study the complexity of conjugacy problems for automorphisms of countable graphs G. Since conjugacy is an equivalence relation on Aut(G), we will study complexity using the invariant descriptive set theory, that is, the Borel reducibility hierarchy. After introducing this background setup, we will give a series of examples of locally finite graphs G whose conjugacy problems have a variety of different complexities. We will see conjugacy problems which are smooth (completely classifiable), complete for hyperfinite relations (E0), complete for essentially countable Borel equivalence relations (E_infinity), and intermediate between E0 and E_infinity.

___________________________________________________________________________________________________________________________________________________


This is going to be an online event. Follow the link below to join the Zoom meeting. Please use your real name to join the meeting.

Title : The 22nd Nankai Logic Colloquium --Samuel Coskey

Time : 16:00pm, Mar. 31, 2023 (Beijing Time) 

Zoom Number : 830 5925 5547

Passcode : 890764

Link : https://us02web.zoom.us/j/83059255547?pwd=V29IcGo0bWdyeitRdHc5eUhBSnNrQT09

_____________________________________________________________________


Best wishes,

Ming Xiao




Cross-Alps Logic Seminar (speaker: Ludovic Patey)

Cross-Alps Logic Seminar
On Friday 31.03.2023 at 16.00
Ludovic Patey (CNRS)
will give a talk on 
Canonical notions of forcing in Reverse Mathematics

Please refer to the usual webpage of our LogicGroup for more details and the abstract of the talk.
The seminar will be held remotely through Webex. Please write to vincenzo.dimonte [at] uniud [dot] it for the link to the event.

The Cross-Alps Logic Seminar is co-organized by the logic groups of Genoa, Lausanne, Turin and Udine as part of our collaboration in the project PRIN 2017 'Mathematical logic: models, sets, computability'.

All the best,
Vincenzo

Logic Seminar Wednesday 29 March 2023 17:00 hrs at NUS by Xie Ruofei

NUS Logic Seminar
Invitation to the Logic Seminar at the National University of Singapore Date: Wednesday, 29 March 2023, 17:00 hrs Place: NUS, Department of Mathematics, S17#05-11 Talk via Zoom: https://nus-sg.zoom.us/j/83049258042?pwd=UWViaWNvTFUrdFdhOHJCdEVydnVkdz09 Meeting ID: 830 4925 8042 Passcode: 1729=x3+y3 Speaker: Xie Ruofei Title: Majorising the Optimal C.E. Supermartingale URL: http://www.comp.nus.edu.sg/~fstephan/logicseminar.html In the article "Highness Properties Close to PA-Completeness", Greenberg, Miller and Nies left the following questions: (1) Is there a finite collection of functionals {Gamma_i:i

This Week in Logic at CUNY

This Week in Logic at CUNY
This Week in Logic at CUNY:

- - - - Monday, Mar 27, 2023 - - - -

Logic and Metaphysics Workshop
Date: Monday, March 27, 4.15-6.15pm (NY time), GC 9206
NOTE: Meetings this semester are in person only (no zoom)
For meeting information, please sign up for our mailing list at https://logic.commons.gc.cuny.edu/about/

Gregory Taylor (CUNY)
Title: First-order logics over fixed domain

Abstract: What we call first-order logic over fixed domain was initiated, in a certain guise, by Peirce around 1885 and championed, albeit in idiosyncratic form, by Zermelo in papers from the 1930s.  We characterize such logics model- and proof-theoretically and argue that they constitute exploration of a clearly circumscribed conception of domain-dependent generality.  Whereas a logic, or family of such, can be of interest for any of a variety of reasons, we suggest that one of those reasons might be that said logic fosters some clarification regarding just what qualifies as a logical concept, a logical operation, or a logical law.



- - - - Tuesday, Mar 28, 2023 - - - -



- - - - Wednesday, Mar 29, 2023 - - - -

The New York City Category Theory Seminar
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York

Speaker:     Jim Otto.

Date and Time:     Wednesday March 29, 2023, 7:00 - 8:30 PM. ZOOM TALK

Title:     P Time, A Bounded Numeric Arrow Category, and Entailments.


Abstract: We revisit the characterization of the P Time functions from our McGill thesis.

1. We build on work of L. Roman (89) on primitive recursion and of A. Cobham (65) and Bellantoni-Cook(92) on P Time.

2. We use base 2 numbers with the digits 1 & 2. Let N be the set of these numbers. We split the tapes of a multi-tape Turing machine each into 2 stacks of digits 1 & 2. These are (modulo allowing an odd numberof stacks) the multi-stack machines we use to study P Time.

3. Let Num be the category with objects the finite products of N and arrows the functions between these. From its arrow category Num^2 we abstract the doctrine (here a category of small categories with chosen structure) PTime of categories with with finite products, base 2 numbers, 2-comprehensions, flat recursion, & safe recursion. Since PTime is a locally finitely presentable category, it has an initial category I. Our characterization is that the bottom of the image of I in Num^2 consists of the P Time functions.

4. We can use I (thinking of its arrows as programs) to run multi-stack machines long enough to get P Time.This is the completeness of the characterization.

5. We cut down the numeric arrow category Num^2, using Bellantoni-Cook growth & time bounds on the functions, to get a bounded numeric arrow category B. B is in the doctrine PTime. This yields the soundness of the characterization.

6. For example, the doctrine of toposes with base 1 numbers, choice, & precisely 2 truth values (which captures much of ZC set theory) likely lacks an initial category, much as there is an initial ring, but no initial field.

7. On the other hand, the L. Roman doctrine PR of categories with finite products, base 1 numbers, & recursion (that is, product stable natural numbers objects) does have an initial category as it consists of the strong models of a finite set of entailments. And is thus locally finitely presentable. We sketch the signature graph for these entailments. And some of these entailments. Similarly (but with more complexity) there are entaiments for the doctrine PTime.





- - - - Thursday, Mar 30, 2023 - - - -



- - - - Friday, Mar 31, 2023 - - - -

Set Theory Seminar
CUNY Graduate Center
Friday, March 31, 12:15pm NY time
Virtual: Please email Victoria Gitman (vgitman@gmail.com) for meeting id.

Benjamin Goodman, CUNY
-correct forcing axioms

The standard method of producing a model of a forcing axiom from a supercompact cardinal in fact gives a model of an even stronger principle: that for every small name a and every  formula  such that  is forceable by and preserved under further forcing in our forcing class, there is a filter  which meets a desired collection of dense sets and also interprets a such that  already holds. I will show how to generalize this result to formulas of higher complexity by starting with slightly stronger large cardinal assumptions, then discuss the bounded versions of these enhanced forcing axioms, their relationships to other similar principles, and their consequences.




Logic Workshop
CUNY Graduate Center
Friday March 31, 2:00pm-3:30pm, Room 6417

Corey Switzer, University of Vienna
Galois-Tukey reductions and canonical structure in the Cichoń diagram

Cardinal invariants of the continuum are cardinal numbers which, roughly, measure how 'badly' CH fails in various mathematical contexts such as analysis and topology. For instance the cardinal  is the least  for which there are  many Lebesgue measure zero sets of reals whose union is not measure zero. Classical facts imply  but the precise value is undetermined in ZFC and depends heavily on the axioms of set theory. Other numbers follow a similar pattern of 'the least size of a set of reals (Borel sets, etc) lacking a classical smallness property'.

The Cichoń diagram displays cardinal invariants related to Lebesgue measure (the null ideal), Baire category (the meager ideal) as well as the bounding and dominating numbers which concern growth rates of functions. Many surprising ZFC-inequalities exist between these cardinals suggesting a rich world living on the reals in various models of set theory. At the combinatorial heart of every proof of a ZFC inequality derives from a Galois-Tukey reduction: the (ZFC-provable) existence of a pair of continuous maps with simple properties that make sense outside of the context of logic and indeed would be sensible to any analyst or topologist.

In this talk we will discuss some recent work in progress on the descriptive complexity of maps witnessing consistent but non-provable implications. We will show using largely computability theoretic methods that in Gödel's constructible universe there are low level projective reductions between any two cardinal invariants - thus CH holds in a very 'definable' way, while in Solovay's model of 'all sets of reals are Lebesgue measurable' (and therefore the axiom of choice fails) there are no non-ZFC provable implications thus these cardinals are all as different as possible.





Next Week in Logic at CUNY:

- - - - Monday, Apr 3, 2023 - - - -

Logic and Metaphysics Workshop
Date: Monday, April 3, 4.15-6.15pm (NY time), GC 9206
NOTE: Meetings this semester are in person only (no zoom)
For meeting information, please sign up for our mailing list at https://logic.commons.gc.cuny.edu/about/

Thomas Ferguson (Czech Academy of Sciences).
Title: Care-theoretic semantics: Problems and non-deterministic solutions

Abstract: In this talk I will present the details of a project of care-theoretic semantics in which a linguistic feature of care–rather than truth–is understood as the fundamental semantic property. I will review the details, including how adopting a bounds consequence position in which bounds are determined by considerations of topic allows one to determine both a theory of inference and theory of meaning on the basis of care alone. I will consider two challenges to the project: that of the reconciliation of topic-theoretic and truth-theoretic bounds (in which we need to acknowledge cases in which a position crosses both types of bounds) and sui generis monstrous content (in which two anodyne sentences together yield a content-theoretic violation). I will show that in both cases intuitions suggest the use of Nmatrices in the style of Avron and consider the merits of their employment in the care-theoretic setting.



- - - - Tuesday, Apr 4, 2023 - - - -



- - - - Wednesday, Apr 5, 2023 - - - -

*** April 5-13, 2023 Spring Recess CUNY Graduate Center ***


- - - - Thursday, Apr 6, 2023 - - - -



- - - - Friday, Apr 7, 2023 - - - -

Set Theory Seminar
CUNY Graduate Center
Friday, April 7, 12:15pm NY time
Virtual: Please email Victoria Gitman (vgitman@gmail.com) for meeting id.
Miha Habič, Bard College at Simon's Rock



*** April 5-13, 2023 Spring Recess CUNY Graduate Center ***



- - - - Other Logic News - - - -


- - - - Web Site - - - -

Find us on the web at:  nylogic.github.io
(site designed, built & maintained by Victoria Gitman)

--------  ADMINISTRIVIA  --------

To subscribe/unsubscribe to this list, please email your request to Jonas.Reitz12@citytech.cuny.edu.

If you have a logic-related event that you would like included in future mailings, please email Jonas.Reitz12@citytech.cuny.edu.

Wednesday seminar

Prague Set Theory Seminar
Dear all, The seminar meets on Wednesday March 29th at 11:00 in the Institute of Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building. Program: Peter Vojtáš -- Considerations on Galois--Tukey motivated by complexity theory and reverse mathematics We will try to walk through the landscape motivated by following publications Peter Vojtas. Generalized Galois-Tukey connections between explicit relations on classical objects of real analysis, IMCP 6 (1993) 619-643 Andreas Blass. Questions and Answers -- A Category Arising in Linear Logic, Complexity Theory, and Set Theory, LMSLN 222 (1995) 61-81 Damir D. Dzhafarov , Carl Mummert. Reverse Mathematics - Problems, Reductions, and Proofs, Springer 2022 to perceive different phenomena, hoping to formulate some new observations and problems Considerations on Galois--Tukey motivated by complexity theory and reverse mathematics. Best, David

(KGRC) guests, video recordings and notes, and four talks

Kurt Godel Research Center
The KGRC welcomes as guests: Clifton Ealy (host: Matthias Aschenbrenner) visits the KGRC until August 15. Franz-Viktor Kuhlmann (host: Matthias Aschenbrenner) visits the KGRC from March 27 to March 31. José Nicolás Nájar Salinas (host: Miguel Moreno) visits the KGRC and gives a talk on March 29, see below. Sergei Starchenko (host: Matthias Aschenbrenner) visits the KGRC from April 16 to April 30 and gives a talk, details to be announced at a later time. Zoltán Vidnyánszky (host: Vera Fischer) visits the KGRC on April 20 and gives a talk, details to be announced at a later time. Fabian Kaak (host: Vera Fischer) visits the KGRC from May 23 to May 26 and gives a short talk, details to be announced at a later time. Jaroslav Šupina (host: Vera Fischer) visits the KGRC from June 18 to June 24 and gives a talk, details to be announced at a later time. Nadiya Kolos (host: Miguel Moreno) visits the KGRC from June 19 to June 23 and gives a talk, details to be announced at a later time. * * * video recordings and slides: For a video recording of part 1 of Miguel Moreno's tutorial, please use https://univienna.zoom.us/rec/share/0CoE9CuBiOXjuXf9dMiFnu63mp4xQCYvQSzjDNFeQT9edwtb9hVwDO6PvBXhSUaH.agwwTP4Mj8fEhKRn and passcode W^9Ej.h3 For part 2, please use https://univienna.zoom.us/rec/share/ltSirTm_O_ONGvGOu-9yJavOaG9QrihlrRtgWNixtSbZZtFTH4gaN7NliBodw44R.dEi0C8qkgxq__Sxp and passcode d3P&V1g$ Notes for the series so can be found here (and will also be updated here after part 3 will be delivered): https://mathematik.univie.ac.at/fileadmin/user_upload/f_mathematik/Events_News/Vortraege_Events/2023-24/KGRC_Set_Theory_2023-03_Miguel_Moreno.pdf For a video recording of Silvain Rideau-Kikuchi's talk, please use https://univienna.zoom.us/rec/share/WZ_GtG4tfySmIRU_O2axDtut8U8bxqNznZvCwk0rFd1nODm43gNH_UNMZUYdmV3j.-1kMmpCZag-qvkL6 and passcode @d1yoKnn * * * Set Theory Research Seminar Kurt Gödel Research Center Tuesday, March 28 "Generalised Descriptive Set Theory, part III" Miguel Moreno (KGRC) During this talk we will discuss where in the generalized Borel-reducibility hierarchy are the isomorphism relation of first order complete theories. These theories are divided into two kinds: classifiable and non-classifiable. To study the classifiable theories case is needed the use of Ehrenfeucht-Frass games. On the other hand the study of the non-classifiable theories is done by using colored ordered trees. The goal of the talk is to see the classifiable theories case and sketch the ideas of non-classifiable theories. Time and Place Talk at 3:00pm in hybrid mode: on-site as well as via Zoom Universität Wien Institut für Mathematik Kolingasse 14-16 1090 Wien 1st floor Seminar room 10 Zoom: If you need the Zoom data and have not received the meeting link by the day before the talk, please contact richard.springer@univie.ac.at! (Students at Uni Wien are required to attend in person.) Please direct any other questions about this talk to vera.fischer@univie.ac.at. * * * Mathematical Colloquium Institut für Mathematik Wednesday, March 29 "Independence Phenomena in Mathematics: Current Obstacles and Scenarios for Solutions" Sandra Müller (TU Wien) The standard axioms of set theory, the Zermelo-Fraenkel axioms (ZFC), do not suffice to answer all questions in mathematics. While this follows abstractly from Kurt Gödel's famous incompleteness theorems, we nowadays know numerous concrete examples for such questions. A large number of problems in set theory, for example, regularity properties such as Lebesgue measurability and the Baire property are not decided - for even rather simple (for example, projective) sets of reals - by ZFC. Even many problems outside of set theory have been shown to be unsolvable, meaning neither their truth nor their failure can be proven from ZFC. A major part of set theory is devoted to attacking this problem by studying various extensions of ZFC and their properties. I will outline some of these extensions and explain current obstacles in understanding their impact on the set theoretical universe together with recent progress on these questions and future scenarios. This work is related to the overall goal to identify the "right" axioms for mathematics. Time and Place Coffee at 2:45pm Talk at 3:15pm Vinum cum Pane following the talk Universität Wien Institut für Mathematik Oskar-Morgenstern-Platz 1 1090 Wien 12th floor Sky Lounge Please direct any questions about this talk to anton.mellit@univie.ac.at or jose.luis.romero@univie.ac.at. * * * Model Theory Research Seminar Kurt Gödel Research Center Wednesday, March 29 "Definability In Abstract Elementary Classes" José Nicolás Nájar Salinas (Fundación Universidad América, CO) The development of definability in the context of Abstract Elementary Classes has been boosted by the recent work of Shelah and Villaveces in which they prove that for every AEC $\mathcal{K}$ in a vocabulary $\tau$, there is a sentence $\psi\in\mathbb{L}_{\beth_2(\kappa)^{+++},\kappa}(\tau)$ axiomatizing where $\kappa$ is the Löwenheim-Skolem number of the class. Vasey enlarges $\tau$ to $\Tilde{\tau}$ and proves that if the AEC is tame and type-short, there is a bijection between the Galois Types of the AEC and the quantifier free types in an infinitary logic $\mathbb{L}_{\lambda,\lambda}(\Tilde{\tau})$ for some suitable $\lambda$, the semantic-syntactic correspondence. We extend the ideas of Vasey to make a partial semantic-syntactic correspondence-like results between Galois types and some types of the logic $\mathbb{L}_{\beth_2(\kappa)^{+++},\kappa}(\tau)$. Part of this is joint work with Andrés Villaveces. Time and Place Talk at 3:00pm Universität Wien Institut für Mathematik Kolingasse 14-16 1090 Wien 1st floor Seminar room 10 Please direct any questions about this talk to matthias.aschenbrenner@univie.ac.at. * * * Logic Colloquium Kurt Gödel Research Center Thursday, March 30 "Constraint Satisfaction Problems: algebraic and model-theoretic challenges to distinguish the easy from the hard" Michael Pinsker (TU Wien) I will give a gentle introduction to current algebraic and model-theoretic methods in the computational complexity of Constraint Satisfaction Problems (CSPs). A CSP is a computational problem where we are given variables and constraints about them; the question is whether the variables can be assigned values such that all constraints are satisfied. Numerous natural computational problems, such as satisfiability of a given system of equations over a field, are CSPs; in fact, any computational problem is Turing-equivalent to a CSP. Any CSP can be modeled by a relational structure, and conversely every relational structure naturally defines a CSP. In view of humanity's continuing quest to distinguish easy from hard problems in general, and the class P (polynomial-time solvable problems, e.g. satisfiability of linear equations over a field) from the class NP (polynomial-time verifiable problems, e.g. satisfiability of a propositional formula) in particular, the question arises which mathematical properties of a relational structure make the corresponding CSP easy and which make it hard. It turns out that particular algebraic invariants of the structure often determine the borderline between different complexity classes. Hence algebraic methods, combined with concepts from model theory as well as from Ramsey theory in the case of infinite structures, yield appropriate tools to determine the computational complexity of CSPs. Time and Place Talk at 3:00pm in hybrid mode: on-site as well as via Zoom Universität Wien Institut für Mathematik Oskar-Morgenstern-Platz 1 1090 Wien 2nd floor room HS 11 Zoom: If you need the Zoom data and have not received the meeting link by the day before the talk, please contact richard.springer@univie.ac.at! (Students at Uni Wien are required to attend in person.) Please direct any questions about this talk to matthias.aschenbrenner@univie.ac.at.

Charla de Slawomir Solecki en el Seminario Colombo Mexicano de Teoría de Conjuntos

Seminario Colombo Mexicano de Teoría de Conjuntos

Seminario Colombo Mexicano de Teoría de Conjuntos

 

March 23

4:00 p.m. - 5:00 p.m. (Colombia time)  

 

Descriptive set theory and closed groups generated by measure preserving transformations
Slawomir Solecki

Cornell University

 

Abstract. The talk is about applications of Descriptive Set Theory to Ergodic Theory. 

The behavior of a measure preserving transformation, even a generic one, is highly non-uniform. In contrast to this observation, a different picture of a very uniform behavior of the closed group generated by a generic measure preserving transformation $T$ has emerged. This picture included substantial evidence that pointed to these groups (for a generic $T$) being all topologically isomorphic to a single group, namely, $L^0$---the topological group of all Lebesgue measurable functions from $[0,1]$ to the circle. In fact, Glasner and Weiss asked if this is the case. 

We will describe the background touched on above, including the descriptive set theoretic background. We will indicate a proof of the following theorem that answers the Glasner--Weiss question in the negative: for a generic measure preserving transformation $T$, the closed group generated by $T$ is not topologically isomorphic to $L^0$. 



Zoom meeting information.
Meeting ID: 856 1882 0721
Passcode: 123456

Nankai Logic Colloquium

Nankai Logic Colloquium

Hello everyone,


This week our weekly Nankai Logic Colloquium is going to be in the morning.


Our speaker this week will be Christian Rosendal from the University of Maryland. This talk is going to take place this Friday,  Mar.24 ,  from 9am to 10am(UTC+8, Beijing time). 

Title: Amenability, optimal transport and cohomology of Banach modules

Abstract: Using tools from the theory of optimal transport, four results concerning isometric actions of amenable topological groups with potentially unbounded orbits are established. Specifically, consider an amenable topological group $G$ with no non-trivial homomorphisms to $\mathbb R$.
If $d$ is a compatible left-invariant metric on $G$, $E\subseteq G$ is a finite subset and $\epsilon>0$, there is a finitely supported probability measure $\beta$ on $G$ so that
$$
\max_{g,h\in E}\, {\sf W}(\beta g, \beta h)<\eps,
$$
where ${\sf W}$ denotes the {\em Wasserstein} or {\em optimal transport} distance between probability measures on the metric space $(G,d)$. When $d$ is the word metric on a finitely generated group $G$, this strengthens a well known theorem of H. Rei\-ter \cite{reiter}. Furthermore, when $G$ is locally compact, $\beta$ may be replaced by an appropriate probability density $f\in L^1(G)$.

Also, when $G\curvearrowright X$ is a continuous isometric action  on a metric space, the space of Lipschitz functions on the quotient $X/\!\!/G$ is isometrically isomorphic to a $1$-complemented subspace of the Lipschitz functions on $X$. And finally every continuous affine isometric action of $G$ on a Banach space has a canonical invariant linear subspace.
These results generalise previous theorems due to Schneider--Thom  and C\'uth--Doucha.

___________________________________________________________________________________________________________________________________________________


This is going to be an online event. Follow the link below to join the Zoom meeting. Please use your real name to join the meeting.

Title : The 21st Nankai Logic Colloquium --Christian Rosendal 

Time : 9:00am, Mar. 24, 2023 (Beijing Time) 

Zoom Number : 849 1206 9207 

Passcode : 929100 

Link : https://zoom.us/j/84912069207?pwd=TTBWakY4OE9sdVNuN2dza3IvemY3Zz09 Christia

_____________________________________________________________________


Best wishes,

Ming Xiao




Logic Seminar Wed 22 March 2023 17:00 hrs at NUS by Takayuki Kihara

NUS Logic Seminar
Invitation to the Logic Seminar at the National University of Singapore Date: Wednesday, 22 March 2023, 17:00 hrs Place: NUS, Department of Mathematics, S17#05-11 Speaker: Kihara Takayuki Title: Topos-theoretic aspect of the degrees of unsolvability URL: http://www.comp.nus.edu.sg/~fstephan/logicseminar.html Abstract: In this talk, we examine the topos-theoretic aspect of the degrees of (computable) unsolvability. One of the main interpretations of constructive mathematics is Kleene's realizability interpretation, which, as is well known, can be relativized by an oracle. In this sense, an oracle can be a factor that causes a change in a model of constructive mathematics. Let us review this observation from another point of view: there is a topos, called the effective topos, based on Kleene's realizability interpretation. And relativizing the realizability interpretation to an oracle yields a subtopos of the effective topos. Thus, the structure of oracles, i.e., the structure of the degrees of unsolvability, is expected to be closely related to the structure of the subtoposes of the effective topos. In this talk, we give a complete correspondence, in a strict sense, between the structure of the degrees of unsolvability and the structure of subtoposes of the effective topos (or its relatives).

This Week in Logic at CUNY

This Week in Logic at CUNY
This Week in Logic at CUNY:

- - - - Monday, Mar 20, 2023 - - - -

Rutgers Logic Seminar 
Monday, March 20, 2pm, Rutgers University, Hill 005
Roman Kossak, CUNY
Absolute Undefinability



Logic and Metaphysics Workshop
Date: Monday, March 20th, 4.15-6.15 (NY time), GC Room 9205
NOTE: Meetings this semester are in person only (no zoom)
For meeting information, please sign up for our mailing list at https://logic.commons.gc.cuny.edu/about/

Speaker: Shawn Simpson (Pitt)
Title: Logic and inference in the sender-receiver model

Abstract: The sender-receiver model was developed by David Lewis to tackle the question of the conventionality of meaning. But many people who cared about the conventionality of meaning did so because they thought it was intimately connected to the conventionality of logic. Since Lewis’s work, only a few attempts have been made to say anything about the nature of logic and inference from the perspective of the sender-receiver model. This talk will look at the what’s been said in that regard, by Skyrms and others, and suggest a few general lessons.



- - - - Tuesday, Mar 21, 2023 - - - -

Models of Peano Arithmetic (MOPA)
Tuesday, March 21, 1:00pm
Virtual (email Victoria Gitman vgitman@gmail.com for meeting id)

Bartosz Wcisło, University of Gdańsk
Satisfaction classes with the full collection scheme

Satisfaction classes are subsets of models of Peano arithmetic which satisfy Tarski's compositional clauses. Alternatively, we can view satisfaction or truth classes as the extension of a fresh predicate T(x) (the theory in which compositional clauses are viewed as axioms is called CT^-).

It is easy to see that CT^- extended with a full induction scheme is not conservative over PA, since it can prove, for instance, the uniform reflection over arithmetic. By a nontrivial argument of Kotlarski, Krajewski, and Lachlan, the sole compositional axioms of CT^- in fact form a conservative extension of PA. Moreover, in order to obtain non-conservativity it is enough to add induction axioms for the Delta_0 formulae containing the truth predicate.

Answering a question of Kaye, we will show that the theory of compositional truth, CT^- with the full collection scheme is a conservative extension of Peano Arithmetic. Following the initial suggestion of Kaye, we will in fact show that any countable recursively saturated model M of PA has an elementary omega_1-like end extension M' such that M' carries a full satisfaction class.



- - - - Wednesday, Mar 22, 2023 - - - -



- - - - Thursday, Mar 23, 2023 - - - -



- - - - Friday, Mar 24, 2023 - - - -

Logic Workshop
CUNY Graduate Center
Friday March 24, 2:00pm-3:30pm, Room 6417
Victoria Gitman CUNY

Parameter-free comprehension in second-order arithmetic

Second-order arithmetic has two types of objects: numbers and sets of numbers, which we think of as the reals. The second-order arithmetic framework has been used successfully to investigate what kinds of real numbers need to exist to prove various significant results in analysis. One of the strongest second-order arithmetic axiomatizations is the theory  consisting of the axioms  (for numbers), the set induction axiom, and comprehension for all second-order formulas with set parameters. How significant is the inclusion of set parameters in the comprehension scheme? Let  be like , but where set parameters are not allowed in the comprehension scheme. Harvey Friedman showed that  and  are equiconsistent because parameter-free comprehension suffices to build a model's version of the constructible universe  inside the model and the 'constructible' reals satisfy . Kanovei recently showed that models of  can be very badly behaved, for example, their sets may not even be closed under complement. Kanovei also showed that there can be nicely behaved models of  in which -comprehension (with set parameters) holds. He constructed his model in a forcing extension by a tree iteration of Sacks forcing. In Kanovei's model, -comprehension (with set parameters) fails and he asked whether this can be improved to -comprehension. In this talk, I will show how to construct a model of -comprehension and  in which -comprehension fails. The model will be constructed in a forcing extension by a tree iteration of Jensen's forcing. Jensen's forcing is a sub-poset of Sacks forcing constructed by Jensen to show that it is consistent to have a non-constructible -definable singleton real (every -definable set of reals is constructible by Shoenfield's Absoluteness).




Next Week in Logic at CUNY:

- - - - Monday, Mar 27, 2023 - - - -

Logic and Metaphysics Workshop
Date: Monday, March 27, 4.15-6.15pm (NY time), GC 9206
NOTE: Meetings this semester are in person only (no zoom)
For meeting information, please sign up for our mailing list at https://logic.commons.gc.cuny.edu/about/

Gregory Taylor (CUNY)
Title: First-order logics over fixed domain

Abstract: What we call first-order logic over fixed domain was initiated, in a certain guise, by Peirce around 1885 and championed, albeit in idiosyncratic form, by Zermelo in papers from the 1930s.  We characterize such logics model- and proof-theoretically and argue that they constitute exploration of a clearly circumscribed conception of domain-dependent generality.  Whereas a logic, or family of such, can be of interest for any of a variety of reasons, we suggest that one of those reasons might be that said logic fosters some clarification regarding just what qualifies as a logical concept, a logical operation, or a logical law.



- - - - Tuesday, Mar 28, 2023 - - - -



- - - - Wednesday, Mar 29, 2023 - - - -

The New York City Category Theory Seminar
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York

Speaker:     Jim Otto.

Date and Time:     Wednesday March 29, 2023, 7:00 - 8:30 PM. ZOOM TALK

Title:     P Time, A Bounded Numeric Arrow Category, and Entailments.


Abstract: We revisit the characterization of the P Time functions from our McGill thesis.

1. We build on work of L. Roman (89) on primitive recursion and of A. Cobham (65) and Bellantoni-Cook(92) on P Time.

2. We use base 2 numbers with the digits 1 & 2. Let N be the set of these numbers. We split the tapes of a multi-tape Turing machine each into 2 stacks of digits 1 & 2. These are (modulo allowing an odd numberof stacks) the multi-stack machines we use to study P Time.

3. Let Num be the category with objects the finite products of N and arrows the functions between these. From its arrow category Num^2 we abstract the doctrine (here a category of small categories with chosen structure) PTime of categories with with finite products, base 2 numbers, 2-comprehensions, flat recursion, & safe recursion. Since PTime is a locally finitely presentable category, it has an initial category I. Our characterization is that the bottom of the image of I in Num^2 consists of the P Time functions.

4. We can use I (thinking of its arrows as programs) to run multi-stack machines long enough to get P Time.This is the completeness of the characterization.

5. We cut down the numeric arrow category Num^2, using Bellantoni-Cook growth & time bounds on the functions, to get a bounded numeric arrow category B. B is in the doctrine PTime. This yields the soundness of the characterization.

6. For example, the doctrine of toposes with base 1 numbers, choice, & precisely 2 truth values (which captures much of ZC set theory) likely lacks an initial category, much as there is an initial ring, but no initial field.

7. On the other hand, the L. Roman doctrine PR of categories with finite products, base 1 numbers, & recursion (that is, product stable natural numbers objects) does have an initial category as it consists of the strong models of a finite set of entailments. And is thus locally finitely presentable. We sketch the signature graph for these entailments. And some of these entailments. Similarly (but with more complexity) there are entaiments for the doctrine PTime.





- - - - Thursday, Mar 30, 2023 - - - -



- - - - Friday, Mar 31, 2023 - - - -

Set Theory Seminar
CUNY Graduate Center
Friday, March 31, 12:15pm NY time
Virtual: Please email Victoria Gitman (vgitman@gmail.com) for meeting id.

Benjamin Goodman, CUNY
-correct forcing axioms

The standard method of producing a model of a forcing axiom from a supercompact cardinal in fact gives a model of an even stronger principle: that for every small name a and every  formula  such that  is forceable by and preserved under further forcing in our forcing class, there is a filter  which meets a desired collection of dense sets and also interprets a such that  already holds. I will show how to generalize this result to formulas of higher complexity by starting with slightly stronger large cardinal assumptions, then discuss the bounded versions of these enhanced forcing axioms, their relationships to other similar principles, and their consequences.




Logic Workshop
CUNY Graduate Center
Friday March 31, 2:00pm-3:30pm, Room 6417
Corey Switzer, University of Vienna




- - - - Other Logic News - - - -


- - - - Web Site - - - -

Find us on the web at:  nylogic.github.io
(site designed, built & maintained by Victoria Gitman)

--------  ADMINISTRIVIA  --------

To subscribe/unsubscribe to this list, please email your request to jreitz@nylogic.org.

If you have a logic-related event that you would like included in future mailings, please email jreitz@nylogic.org. v

Wednesday seminar

Prague Set Theory Seminar
Dear all, The seminar meets on Wednesday March 22nd at 11:00 in the Institute of Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building. Program: David Uhrik -- Hajnal--Máté Graphs and Cohen Reals We will study Hajnal--Máté (HM) graphs. The first construction of an HM graph was from the diamond+ principle. Since then several other constructions were provided with additional interesting properties, e.g. having no triangles. We will survey results about this class of graphs and provide a construction of a triangle free HM graph in a model after adding a single Cohen real. Time permitting we will introduce a generalization, so-called 𝛿-Hajnal--Máté graphs, and prove some of their basic properties and deduce a weak partition relation on ω_2. Best, David

(KGRC) Set Theory Seminar talk and Geometry and Analysis on Groups Seminar talk

Kurt Godel Research Center
The KGRC welcomes as guests: Martin Hils (host: Matthias Aschenbrenner) visits the KGRC until March 31. Clifton Ealy (host: Matthias Aschenbrenner) visits the KGRC until August 15. Lou van den Dries (host: Matthias Aschenbrenner) visits the KGRC from March 10 to March 22. Chieu-Minh Tran (host: Matthias Aschenbrenner) visits the KGRC from March 19 to March 22 and gives a talk on March 21, see below. Franz-Viktor Kuhlmann (host: Matthias Aschenbrenner) visits the KGRC from March 27 to March 31. José Nicolás Nájar Salinas (host: Miguel Moreno) visits the KGRC and gives a talk on March 29, details to be announced at a later time. Sergei Starchenko (host: Matthias Aschenbrenner) visits the KGRC from April 16 to April 30 and gives a talk, details to be announced at a later time. Zoltán Vidnyánszky (host: Vera Fischer) visits the KGRC on April 20 and gives a talk, details to be announced at a later time. Jaroslav Šupina (host: Vera Fischer) visits the KGRC from June 18 to June 24 and gives a talk, details to be announced at a later time. * * * Set Theory Research Seminar Kurt Gödel Research Center Tuesday, March 21 "Generalised Descriptive Set Theory, part II" Miguel Moreno (KGRC) We have introduced the notions of K-Borel class, K-analytic class, K-analytic-coanalytic class, K-Borel* class in the previous talk. In descriptive set theory the Borel class, the analytic-coanalytic class, and the Borel* class are the same class, we showed that this doesn't hold in the generalized descriptive set theory. In this talk, we will show the consistency of "K-Borel* class is equal to the K-analytic class". This was initially proved by Hyttinen and Weinstein (former Kulikov), under the assumption V=L. We will show a different proof that shows that this holds in L but also can be forced by a cofinality-preserving GCH-preserving forcing from a model of GCH, but also by a 3.99 \mu(A)$. We also show a more general result for the product of two sets, which can be seen as a Brunn-Minkowski-type inequality for sets with small measure in $\mathrm{SO}(3,\mathbb{R})$. (Joint with Yifan Jing and Ruixiang Zhang) Time and Place Talk at 3:00pm Universität Wien Institut für Mathematik Oskar-Morgenstern-Platz 1 1090 Wien 9th floor room BZ 9 Please direct any questions about this talk to matthias.aschenbrenner@univie.ac.at.

Logic Seminar today in person in S17#05-11

NUS Logic Seminar
Hello, here just a reminder for the talk of Liu Shixiao in the logic seminar today at 17:00 hrs (now) on Forcing with Density Requirements. The abstract is: In the first half of the talk I shall be proving the Properness of Mathias forcing with lower density requirements. In the second half of the talk I shall demonstrate the difficulty in applying this method (and some other commonly used methods) to Silver forcing with lower density requirement. The location is S17#05-11 in the Department of Mathematics, NUS. Best regards, Frank

Nankai Logic Colloquium

Nankai Logic Colloquium

Hello everyone,

This week our weekly Nankai Logic Colloquium is going to be in the morning.

Our speaker this week will be Konstantin Slutsky from Iowa State University. This talk is going to take place this Friday, Mar. 17,  from 9am to 10am(UTC+8, Beijing time). 

Title: Partial actions and orbit equivalence relations

Abstract: In this talk, we will discuss the framework of partial actions for constructing orbit equivalent actions of Polish groups. While related ideas have been employed in ergodic theory and Borel dynamics for many years, the particular viewpoint of partial actions simplifies construction of orbit equivalent actions of distinct groups.  
As an application, we will present a Borel version of Katok's representation theorem for multidimensional Borel flows. One-dimensional flows are closely connected to actions of $\mathbb{Z}$ via the so-called "flow under a function" construction.  This appealing geometric picture does not generalize to higher dimensions.  Within the ergodic theoretical framework, Katok introduced the concept of a special flow as a way to connect multidimensional $\mathbb{R}^d$ and $\mathh{Z}^d$ actions.  We will show that similar connections continue to hold in Borel dynamics.
Another illustration of the partial actions techniques that we intend to touch is the following result: a Borel equivalence relation generated by a free $\mathbb{R}$-flow can also be generated by a free action of any non-discrete and non-compact Polish group. This is in contrast with the situation for discrete groups, where amenability distinguishes groups that can and cannot generate free finite measure-preserving hyperfinite actions.

___________________________________________________________________________________________________________________________________________________


This is going to be an online event. Follow the link below to join the Zoom meeting. Please use your real name to join the meeting.

Title:                The 20th Nankai Logic Colloquium --Konstantin Slutsky

Time:                9:00am, Mar. 17, 2023 (Beijing Time)

Zoom Number:811 5076 2263

Passcode:         201148

Link:                https://zoom.us/j/81150762263?pwd=UmdvRkVEUjI2MHlONHQrdmQrRFJyZz09

_____________________________________________________________________


Best wishes,

Ming Xiao




Charla de Cesar Corral en el Seminario Colombo Mexicano de Teoría de Conjuntos

Seminario Colombo Mexicano de Teoría de Conjuntos

Seminario Colombo Mexicano de Teoría de Conjuntos

 

Marzo 16

4:00 p.m. - 5:00 p.m. (Hora de Colombia)  

 

Familias MAD Fin-intersecting
Cesar Corral

Universidad de York

 

Abstract. Diremos que una familia MAD es pseudocompacta, si el hiperespacio de su \Psi-espacio lo es. Algunos resultados de Ginsgurg establecen relaciones entre propiedades del tipo compacidad de un espacio y su hiperespacio, además de que también preguntó la relación entre la pseudocompacidad de X^\omega y la de su hiperespacio exp(X).

Más tarde, Hrusak, Hernández y Martinez-Ruiz mostraron que existe un subespacio X de \beta(\omega) tal que X^\omega es pseudocompacto pero exp(X) no lo es. En el mismo trabajo, demostraron que, consistentemente, toda familia MAD es pseudocompacta, pero contrastantemente, también mostraron la consistencia de que hay una MAD no pseudocompacta. La existencia de familias MAD pseudocompactas en \textsf{ZFC} es aún desconocida. 
Para atacar este problema, introduciremos las familias MAD Fin-intersecting, mostraremos que estas familias son pseudocompactas y mostraremos su existencia en diferentes modelos, incluyendo algunos en los cuales la existencia de familias MAD pseudocompactas era aún desconocido.

Este es un trabajo conjunto con Vinicius de Oliveira Rodrigues.


Zoom meeting information.
Meeting ID: 856 1882 0721
Passcode: 123456

Cross-Alps Logic Seminar (speaker: Victor Selivanov)

Cross-Alps Logic Seminar
On Friday 17.03.2023 at 16.00
Victor Selivanov (Institute of Informatics Systems, Novosibirsk)
will give a talk on 
Boole vs Wadge: Comparing Basic Tools of Descriptive Set Theory

Please refer to the usual webpage of our LogicGroup for more details and the abstract of the talk.
The seminar will be held remotely through Webex. Please write to vincenzo.dimonte [at] uniud [dot] it for the link to the event.

The Cross-Alps Logic Seminar is co-organized by the logic groups of Genoa, Lausanne, Turin and Udine as part of our collaboration in the project PRIN 2017 'Mathematical logic: models, sets, computability'.

All the best,
Vincenzo

CosmoCaixa Barcelona: Joel Hamkins: pensament estratègic en jocs infinits

Barcelona Logic Seminar
Dear All,
Just a reminder that you may get a 3 Euros admission fee for the Cosmocaixa museum, on the occasion of Joel hamkins’ talk. Go to the link below to get the entrance ticket and use the following code:

CCX23UNIVERSITAT 

I strongly encourage you to attend Joel’s talk, and visit the Cosmocaixa!
See you there!
Joan


Benvolguts,
us envio l’anunci de la conferència que farà Joel Hamkins al Cosmocaixa el dia 16 de març a les 7. L’entrada val 6 Euros, però us puc donar un codi que la redueix a 3. Inclou la visita al Cosmocaixa.

Joel Hamkins: pensament estratègic en jocs infinits 

https://cosmocaixa.org/ca/p/pensament-estrategic-en-jocs-infinits_a122155152 . 

Espero que vingueu,
Joan


Dear All,
here is the announcement of the talk by Joel Hamkins he will give at Cosmocaixa (Science Museum in Barcelona) on March 16, 7pm. The entry fee is 6 Euros, but I can give you a code that reduces it to 3 Euros. It includes the entrance to the museum
  
Joel Hamkins: Strategic Thinking in Infinite Games

https://cosmocaixa.org/ca/p/pensament-estrategic-en-jocs-infinits_a122155152 . 

Hope to see you there!
Joan


neal
Joan Bagaria 
ICREA Research Professor 
Universitat de Barcelona
Departament de Matemàtiques i Informàtica
Gran Via de les Corts Catalanes 585
08007 Barcelona
Catalonia 

Phone: +34 93 402 1609
joan.bagaria@icrea.cat
bagaria@ub.edu



Joan Bagaria 
ICREA Research Professor 
Universitat de Barcelona
Departament de Matemàtiques i Informàtica
Gran Via de les Corts Catalanes 585
08007 Barcelona
Catalonia 

Phone: +34 93 402 1609
joan.bagaria@icrea.cat
bagaria@ub.edu


Wednesday seminar

Prague Set Theory Seminar
Dear all, The seminar meets on Wednesday March 15th at 11:00 in the Institute of Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building. There is no fixed program yet. Participants are encouraged to bring their topics and questions to share. (Chris is leaving for couple of months at the end of the week, so this will be for some time the last opportunity to ask him something. ;-) Best, David

This Week in Logic at CUNY

This Week in Logic at CUNY
This Week in Logic at CUNY:

- - - - Monday, Mar 13, 2023 - - - -

Logic and Metaphysics Workshop
Date: Monday, March 13, 4.15-6.15pm (NY time), GC 9206
NOTE: Meetings this semester are in person only (no zoom)
For meeting information, please sign up for our mailing list at https://logic.commons.gc.cuny.edu/about/

Melvin Fitting (CUNY)
Title: On Kripke’s proof of Kripke completeness

Abstract: Saul Kripke announced his possible world semantics in 1959, and `published his proof of axiomatic completeness for the standard modal logics of the time in 1963.  It is very unlike the standard completeness proof used today, which involves a Lindenbaum/Henkin construction and produces canonical models.  Kripke’s proof involved tableaus, in a format that is difficult to follow, and uses tableau construction algorithms that are complex and somewhat error prone to describe. I will first discuss Kripke’s proof, then the historical origins of the modern version.  Then I will show that completeness, proved Kripke style, could actually have been done in the Lindenbaum/Henkin way, thus simplifying things considerably.  None of this is new but, with the parts collected together it is an interesting story. “In my end is my beginning”.


- - - - Tuesday, Mar 14, 2023 - - - -

Models of Peano Arithmetic (MOPA)
Tuesday, March 14, 1:00pm
Virtual (email Victoria Gitman vgitman@gmail.com for meeting id)

Bartosz Wcisło, University of Gdańsk
Satisfaction classes with the full collection scheme

Satisfaction classes are subsets of models of Peano arithmetic which satisfy Tarski's compositional clauses. Alternatively, we can view satisfaction or truth classes as the extension of a fresh predicate T(x) (the theory in which compositional clauses are viewed as axioms is called CT^-).

It is easy to see that CT^- extended with a full induction scheme is not conservative over PA, since it can prove, for instance, the uniform reflection over arithmetic. By a nontrivial argument of Kotlarski, Krajewski, and Lachlan, the sole compositional axioms of CT^- in fact form a conservative extension of PA. Moreover, in order to obtain non-conservativity it is enough to add induction axioms for the Delta_0 formulae containing the truth predicate.

Answering a question of Kaye, we will show that the theory of compositional truth, CT^- with the full collection scheme is a conservative extension of Peano Arithmetic. Following the initial suggestion of Kaye, we will in fact show that any countable recursively saturated model M of PA has an elementary omega_1-like end extension M' such that M' carries a full satisfaction class.





- - - - Wednesday, Mar 15, 2023 - - - -

The New York City Category Theory Seminar
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York
Speaker:     Jens Hemelaer, University of Antwerp.
Date and Time:     Wednesday March 15, 2023, 7:00 - 8:30 PM. IN PERSON TALK.
Title:     EILC toposes.

Abstract: In topos theory, local connectedness of a geometric morphism is a very geometric property, in the sense that it is stable under base change, can be checked locally, and so on. In some situations however, the weaker property of being essential is easier to verify. In this talk, we will discuss EILC toposes: toposes E such that any essential geometric morphism with codomain E is automatically locally connected. It turns out that many toposes of interest are EILC, including toposes of sheaves on Hausdorff spaces and classifying toposes of compact groups.



- - - - Thursday, Mar 16, 2023 - - - -



- - - - Friday, Mar 17, 2023 - - - -

Set Theory Seminar
CUNY Graduate Center
Friday, March 17, 12:15pm NY time
Virtual: Please email Victoria Gitman (vgitman@gmail.com) for meeting id.

Jonathan Osinski, University of Hamburg
Model-Theoretic Characterizations of Weak Vopěnka's Principle

It has been known since the 1980s that Vopěnka's Principle (VP) is equivalent to certain statements about logics, e.g. to the schema 'Every logic has a compactness cardinal.' On the other hand, it was only recently shown by Trevor Wilson that a related statement statement called Weak Vopěnka's Principle (WVP) is strictly weaker than VP. In fact, Joan Bagaria and Wilson showed that WVP is equivalent to the existence of -strong cardinals for all natural numbers . We generalize logical characterizations of strong cardinals to achieve a characterization of -strong cardinals and therefore of WVP in terms of properties of strong logics. This is partly joint work with Will Boney and partly with Trevor Wilson.




Logic Workshop
CUNY Graduate Center
Friday March 17, 2:00pm-3:30pm, Room 6417

Filippo Calderoni, Rutgers University
Rotation equivalence and rigidity

The theory of countable Borel equivalence relations analyzes the actions of countable groups on Polish spaces. The main question studied is how much information is encoded by the corresponding orbit space. The amount of encoded information reflects the extent to which the action is rigid.

In this talk we will discuss rigidity results for the action of the group of rational rotations. In particular we will analyze the rotation equivalence on spheres in higher dimension. This is connected to superrigidity results of Margulis and to Zimmer’s program about the actions of discrete subgroups of Lie groups on manifolds.



Next Week in Logic at CUNY:

- - - - Monday, Mar 20, 2023 - - - -

Rutgers Logic Seminar 
Monday, March 20, 2pm, Rutgers University, Hill 005
Roman Kossak, CUNY
Absolute Undefinability



Logic and Metaphysics Workshop
Date: Monday, March 20, 4.15-6.15pm (NY time), GC 9206
NOTE: Meetings this semester are in person only (no zoom)
For meeting information, please sign up for our mailing list at https://logic.commons.gc.cuny.edu/about/

Gregory Taylor (CUNY)
Title: First-order logics over fixed domain

Abstract: What we call first-order logic over fixed domain was initiated, in a certain guise, by Peirce around 1885 and championed, albeit in idiosyncratic form, by Zermelo in papers from the 1930s.  We characterize such logics model- and proof-theoretically and argue that they constitute exploration of a clearly circumscribed conception of domain-dependent generality.  Whereas a logic, or family of such, can be of interest for any of a variety of reasons, we suggest that one of those reasons might be that said logic fosters some clarification regarding just what qualifies as a logical concept, a logical operation, or a logical law.



- - - - Tuesday, Mar 21, 2023 - - - -



- - - - Wednesday, Mar 22, 2023 - - - -



- - - - Thursday, Mar 23, 2023 - - - -



- - - - Friday, Mar 24, 2023 - - - -

Logic Workshop
CUNY Graduate Center
Friday March 24, 2:00pm-3:30pm, Room 6417
Victoria Gitman CUNY



- - - - Other Logic News - - - -


- - - - Web Site - - - -

Find us on the web at:  nylogic.github.io
(site designed, built & maintained by Victoria Gitman)

--------  ADMINISTRIVIA  --------

To subscribe/unsubscribe to this list, please email your request to jreitz@nylogic.org.

If you have a logic-related event that you would like included in future mailings, please email jreitz@nylogic.org

(KGRC) talks on Tuesday, March 14 and Thursday, March 16

Kurt Godel Research Center
The KGRC welcomes as guests: Martin Hils (host: Matthias Aschenbrenner) visits the KGRC until March 31. Clifton Ealy (host: Matthias Aschenbrenner) visits the KGRC until August 15. Lou van den Dries (host: Matthias Aschenbrenner) visits the KGRC from March 10 to March 22. Silvain Rideau-Kikuchi (host: Matthias Aschenbrenner) visits the KGRC from March 15 to March 20 and gives a talk, see below. José Nicolás Nájar Salinas (host: Miguel Moreno) visits the KGRC and gives a talk on March 29, details to be announced at a later time. Sergei Starchenko (host: Matthias Aschenbrenner) visits the KGRC from April 16 to April 30 and gives a talk, details to be announced at a later time. * * * For a video recording of Juris Steprāns's talk, please use https://univienna.zoom.us/rec/share/_U6vJ6rbIaT1WaoflIav52OiR4GsAQ-W3Aw00aD4jb08xvlf7C4QoQJyD_KlQkEc.h7MOui67bVxLr9Cl and passcode jTi%8uqf * * * Set Theory Research Seminar Kurt Gödel Research Center Tuesday, March 14 "Generalised Descriptive Set Theory, part I" Miguel Moreno (KGRC) This is the first of three talks about Generalised Descriptive Set Theory. The aim of this talk is to introduce the notions of K‑Borel class, K‑analytic class, K‑analytic-coanalytic class, K‑Borel* class, and show the relation between these classes. Time and Place Talk at 3:00pm in hybrid mode: on-site as well as via Zoom Universität Wien Institut für Mathematik Kolingasse 14-16 1090 Wien 1st floor Seminar room 10 Zoom: If you need the Zoom data and have not received the meeting link by the day before the talk, please contact richard.springer@univie.ac.at! (Students at Uni Wien are required to attend in person.) Please direct any other questions about this talk to vera.fischer@univie.ac.at. * * * Logic Colloquium Kurt Gödel Research Center Thursday, March 16 "Multi topological fields, approximations and NTP2" Silvain Rideau-Kikuchi (U Paris Diderot, FR) (Joint work with S. Montenegro) The striking resemblance between the behaviour of pseudo-algebraically closed, pseudo real closed and pseudo p-adically fields has lead to numerous attempts at describing their properties in a unified manner. In this talk I will present another of these attempts: the class of pseudo-T-closed fields, where T is an enriched theory of fields. These fields verify a « local-global » principle with respect to models of T for the existence of points on varieties. Although it very much resembles previous such attempts, our approach is more model theoretic in flavour, both in its presentation and in the results we aim for. The first result I would like to present is an approximation result, generalising a result of Kollar on PAC fields, respectively Johnson on henselian fields. This result can be rephrased as the fact that existential closeness in certain topological enrichments come for free from existential closeness as a field. The second result is a (model theoretic) classification result for bounded pseudo-T-closed fields, in the guise of the computation of their burden. One of the striking consequence of these two results is that a bounded perfect PAC field with n independent valuations has burden n and, in particular, is NTP2. Time and Place Talk at 3:00pm in hybrid mode: on-site as well as via Zoom Universität Wien Institut für Mathematik Oskar-Morgenstern-Platz 1 1090 Wien 2nd floor room HS 11 Zoom: If you need the Zoom data and have not received the meeting link by the day before the talk, please contact richard.springer@univie.ac.at! (Students at Uni Wien are required to attend in person.) Please direct any other questions about this talk to matthias.aschenbrenner@univie.ac.at.

Nankai Logic Colloquium

Nankai Logic Colloquium

Hello everyone,


This week our weekly Nankai Logic Colloquium is going to be in the afternoon.


Our speaker this week will be Vladimir Kanovei from the Institute for Information Transmission Problems, RAS. This talk is going to take place this Friday, Mar.10, from 4pm to 5pm(UTC+8, Beijing time). 


Title:
On the significance of parameters in the choice and сomprehension schemata in the 2nd-order Peano arithmetic Abstract Parameters are free variables in various axiom schemata in PA, ZFC, and other similar theories. Given an axiom schema S, we let S* be the parameter-free sub-schema. Kreisel (A survey of proof theory, JSL 1968) was one of those who paid attention to the comparison of some schemata in second-order PA and their parameter-free versions. In particular, Kreisel noted that [...] if one is convinced of the significance of something like agiven axiom schema, it is natural to study details, such as the effect of parameters. This talk is devoted to the effect of parameters in the schemata of Comprehension and Choice in second-order arithmetic.
___________________________________________________________________________________________________________________________________________________


This is going to be an online event. Follow the link below to join the Zoom meeting. Please use your real name to join the meeting.

Title:                The 19th Nankai Logic Colloquium --Vladimir Kanovei
Time:                16:00pm, Mar. 10, 2023 (Beijing Time)
Zoom Number:844 4116 3813
Passcode:         628524
Link:                 https://zoom.us/j/84441163813?pwd=WFlSbThMbldUeVZYZncrTGVyYmp5QT09


_____________________________________________________________________


Best wishes,

Ming Xiao




UPDATE - This Week in Logic at CUNY

This Week in Logic at CUNY
Hi everyone,

A quick update - Unfortunately, Dr. Weinert will be unable to speak on March 10, so the Logic Workshop is canceled this week.

Best,
Jonas



This Week in Logic at CUNY:

- - - - Monday, Mar 6, 2023 - - - -

Rutgers Logic Seminar 
Monday, March 6, 2pm, Rutgers University, Hill 005
Will Adkisson, UIC
The Strong and Super Tree Property

Logic and Metaphysics Workshop
Date: Monday, March 6, 4.15-6.15pm (NY time), GC 9206
NOTE: Meetings this semester are in person only (no zoom)
For meeting information, please sign up for our mailing list at https://logic.commons.gc.cuny.edu/about/
Gary Ostertag (CUNY/Mount Sinai)

Title: Lewis on accommodation and representation de re

Abstract: Recall Lumpl, the lump of clay out of which the statue Goliath is fashioned. While (1) ‘Lumpl could have survived a squashing’ is true, (2) ‘Goliath could have survived a squashing’ is false, it being after all essential to Goliath, but not to Lumpl, that it be a statue. We have here an example of what David Lewis (1986) called “the inconstancy of representation de re”. For Lewis, the inconstancy does not amount to inconsistency, but rather points to the context-sensitivity of de re modal predication: (1) and (2) make implicit, context-sensitive reference to different counterpart relations. Once we recognize this, Lewisians argue, it becomes clear how our intuitive truth-conditional judgments are fully consistent. As I show, however, the conversational rule that triggers the implicit reference not only fails to license the reference shift, it effectively prohibits it. The upshot is that counterpart theory is deprived of a central motivation.

 



- - - - Tuesday, Mar 7, 2023 - - - -

Models of Peano Arithmetic (MOPA)
Tuesday, March 7, 1:00pm
Virtual (email Victoria Gitman vgitman@gmail.com for meeting id)

Bellaouar Djamel, University 08 Mai 1945 Guelma
Some generalizations on the representation of unlimited natural numbers

Based on permanence principles of nonstandard analysis and as a continuation of the papers [1-3], we present some notes and questions on the representation of unlimited natural numbers. As a natural generalization, let  be an unlimited  by  matrix with integer entries (i.e one of its integer entries is unlimited). Here we prove that every unlimited matrix  with integer entries can be written as the sum of a limited matrix S with integer entries and the product of two unlimited matrices  and  with integer entries, that is, . For further research, we propose several matrix representation forms.

Finally, we consider the numbers of the form  where , are integers, which are called Gaussian integers. In the case when  or  is unlimited, the number  is said to be unlimited. Also, some notes on the representation of unlimited Gaussian integers are given.

[1] A. Boudaoud, La conjecture de Dickson et classes particulière d'entiers, Ann. Math. Blaise Pascal. 13 (2006), 103-109.
[2] A. Boudaoud and D. Bellaouar, Representation of integers: A nonclassical point of view, J. Log. Anal. 12:4 (2020) 1-31.
[3] K. Hrbacek, On Factoring of unlimited integers, J. Log. Anal. 12:5 (2020) 1-6.




- - - - Wednesday, Mar 8, 2023 - - - -



- - - - Thursday, Mar 9, 2023 - - - -



- - - - Friday, Mar 10, 2023 - - - -

Logic Workshop - TODAY'S WORKSHOP IS CANCELLED
CUNY Graduate Center
Friday March 10, 2:00pm-3:30pm, Room 6417



Set Theory Seminar
CUNY Graduate Center
Friday, March 10, 12:15pm NY time
Virtual: Please email Victoria Gitman (vgitman@gmail.com) for meeting id.
James Holland, Rutgers University



Next Week in Logic at CUNY:

- - - - Monday, Mar 13, 2023 - - - -

Logic and Metaphysics Workshop
Date: Monday, March 13, 4.15-6.15pm (NY time), GC 9206
NOTE: Meetings this semester are in person only (no zoom)
For meeting information, please sign up for our mailing list at https://logic.commons.gc.cuny.edu/about/

Melvin Fitting (CUNY)
Title: On Kripke’s proof of Kripke completeness

Abstract: Saul Kripke announced his possible world semantics in 1959, and `published his proof of axiomatic completeness for the standard modal logics of the time in 1963.  It is very unlike the standard completeness proof used today, which involves a Lindenbaum/Henkin construction and produces canonical models.  Kripke’s proof involved tableaus, in a format that is difficult to follow, and uses tableau construction algorithms that are complex and somewhat error prone to describe. I will first discuss Kripke’s proof, then the historical origins of the modern version.  Then I will show that completeness, proved Kripke style, could actually have been done in the Lindenbaum/Henkin way, thus simplifying things considerably.  None of this is new but, with the parts collected together it is an interesting story. “In my end is my beginning”.


- - - - Tuesday, Mar 14, 2023 - - - -

Models of Peano Arithmetic (MOPA)
Tuesday, March 14, 1:00pm
Virtual (email Victoria Gitman vgitman@gmail.com for meeting id)
Bartosz Wcisło, University of Gdańsk




- - - - Wednesday, Mar 15, 2023 - - - -

The New York City Category Theory Seminar
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York
Speaker:     Jens Hemelaer, University of Antwerp.
Date and Time:     Wednesday March 15, 2023, 7:00 - 8:30 PM. IN PERSON TALK.
Title:     EILC toposes.

Abstract: In topos theory, local connectedness of a geometric morphism is a very geometric property, in the sense that it is stable under base change, can be checked locally, and so on. In some situations however, the weaker property of being essential is easier to verify. In this talk, we will discuss EILC toposes: toposes E such that any essential geometric morphism with codomain E is automatically locally connected. It turns out that many toposes of interest are EILC, including toposes of sheaves on Hausdorff spaces and classifying toposes of compact groups.



- - - - Thursday, Mar 16, 2023 - - - -



- - - - Friday, Mar 17, 2023 - - - -

Set Theory Seminar
CUNY Graduate Center
Friday, March 17, 12:15pm NY time
Virtual: Please email Victoria Gitman (vgitman@gmail.com) for meeting id.
Jonathan Osinski, University of Hamburg


Logic Workshop
CUNY Graduate Center
Modality TBA
Friday March 17, 2:00pm-3:30pm, Room 6417
Filippo Calderoni, Rutgers University


- - - - Other Logic News - - - -


- - - - Web Site - - - -

Find us on the web at:  nylogic.github.io
(site designed, built & maintained by Victoria Gitman)

--------  ADMINISTRIVIA  --------

To subscribe/unsubscribe to this list, please email your request to jreitz@nylogic.org.

If you have a logic-related event that you would like included in future mailings, please email jreitz@nylogic.org

Charla de Paul Szeptycki en el Seminario Colombo Mexicano de Teoría de Conjuntos

Seminario Colombo Mexicano de Teoría de Conjuntos

Seminario Colombo Mexicano de Teoría de Conjuntos

 

March 9

4:00 p.m. - 5:00 p.m. (Colombia time)  

 

A Ramsey-theoretic strengthening of sequential compactness
Paul Szeptycki

York University

 

Abstract. We define a topological space $X$ to be $n$-Ramsey if for every map $f: [\omega]^n \rightarrow X$ there is an infinite set $M$ and a point $x \in X$ such that $f \uphaproonright [M]^n$ converges to $x$ in a natural sense. Sequentially compact spaces are precisely the $1$-Ramsey spaces and any $n+1$-Ramsey space is $n$-Ramsey.  We discuss basic results about these new classes of spaces, directions of current work in progress and some open problems.  



Zoom meeting information.
Meeting ID: 856 1882 0721
Passcode: 123456


This Week in Logic at CUNY

This Week in Logic at CUNY
This Week in Logic at CUNY:

- - - - Monday, Mar 6, 2023 - - - -

Rutgers Logic Seminar 
Monday, March 6, 2pm, Rutgers University, Hill 005
Will Adkisson, UIC
The Strong and Super Tree Property

Logic and Metaphysics Workshop
Date: Monday, March 6, 4.15-6.15pm (NY time), GC 9206
NOTE: Meetings this semester are in person only (no zoom)
For meeting information, please sign up for our mailing list at https://logic.commons.gc.cuny.edu/about/
Gary Ostertag (CUNY/Mount Sinai)

Title: Lewis on accommodation and representation de re

Abstract: Recall Lumpl, the lump of clay out of which the statue Goliath is fashioned. While (1) ‘Lumpl could have survived a squashing’ is true, (2) ‘Goliath could have survived a squashing’ is false, it being after all essential to Goliath, but not to Lumpl, that it be a statue. We have here an example of what David Lewis (1986) called “the inconstancy of representation de re”. For Lewis, the inconstancy does not amount to inconsistency, but rather points to the context-sensitivity of de re modal predication: (1) and (2) make implicit, context-sensitive reference to different counterpart relations. Once we recognize this, Lewisians argue, it becomes clear how our intuitive truth-conditional judgments are fully consistent. As I show, however, the conversational rule that triggers the implicit reference not only fails to license the reference shift, it effectively prohibits it. The upshot is that counterpart theory is deprived of a central motivation.

 



- - - - Tuesday, Mar 7, 2023 - - - -

Models of Peano Arithmetic (MOPA)
Tuesday, March 7, 1:00pm
Virtual (email Victoria Gitman vgitman@gmail.com for meeting id)

Bellaouar Djamel, University 08 Mai 1945 Guelma
Some generalizations on the representation of unlimited natural numbers

Based on permanence principles of nonstandard analysis and as a continuation of the papers [1-3], we present some notes and questions on the representation of unlimited natural numbers. As a natural generalization, let  be an unlimited  by  matrix with integer entries (i.e one of its integer entries is unlimited). Here we prove that every unlimited matrix  with integer entries can be written as the sum of a limited matrix S with integer entries and the product of two unlimited matrices  and  with integer entries, that is, . For further research, we propose several matrix representation forms.

Finally, we consider the numbers of the form  where , are integers, which are called Gaussian integers. In the case when  or  is unlimited, the number  is said to be unlimited. Also, some notes on the representation of unlimited Gaussian integers are given.

[1] A. Boudaoud, La conjecture de Dickson et classes particulière d'entiers, Ann. Math. Blaise Pascal. 13 (2006), 103-109.
[2] A. Boudaoud and D. Bellaouar, Representation of integers: A nonclassical point of view, J. Log. Anal. 12:4 (2020) 1-31.
[3] K. Hrbacek, On Factoring of unlimited integers, J. Log. Anal. 12:5 (2020) 1-6.




- - - - Wednesday, Mar 8, 2023 - - - -



- - - - Thursday, Mar 9, 2023 - - - -



- - - - Friday, Mar 10, 2023 - - - -

Logic Workshop
CUNY Graduate Center
Modality TBA
Friday March 10, 2:00pm-3:30pm, Room 6417
Thilo Weinert, University of Vienna


Set Theory Seminar
CUNY Graduate Center
Friday, March 10, 12:15pm NY time
Virtual: Please email Victoria Gitman (vgitman@gmail.com) for meeting id.
James Holland, Rutgers University



Next Week in Logic at CUNY:

- - - - Monday, Mar 13, 2023 - - - -

Logic and Metaphysics Workshop
Date: Monday, March 13, 4.15-6.15pm (NY time), GC 9206
NOTE: Meetings this semester are in person only (no zoom)
For meeting information, please sign up for our mailing list at https://logic.commons.gc.cuny.edu/about/

Melvin Fitting (CUNY)
Title: On Kripke’s proof of Kripke completeness

Abstract: Saul Kripke announced his possible world semantics in 1959, and `published his proof of axiomatic completeness for the standard modal logics of the time in 1963.  It is very unlike the standard completeness proof used today, which involves a Lindenbaum/Henkin construction and produces canonical models.  Kripke’s proof involved tableaus, in a format that is difficult to follow, and uses tableau construction algorithms that are complex and somewhat error prone to describe. I will first discuss Kripke’s proof, then the historical origins of the modern version.  Then I will show that completeness, proved Kripke style, could actually have been done in the Lindenbaum/Henkin way, thus simplifying things considerably.  None of this is new but, with the parts collected together it is an interesting story. “In my end is my beginning”.


- - - - Tuesday, Mar 14, 2023 - - - -

Models of Peano Arithmetic (MOPA)
Tuesday, March 14, 1:00pm
Virtual (email Victoria Gitman vgitman@gmail.com for meeting id)
Bartosz Wcisło, University of Gdańsk




- - - - Wednesday, Mar 15, 2023 - - - -

The New York City Category Theory Seminar
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York
Speaker:     Jens Hemelaer, University of Antwerp.
Date and Time:     Wednesday March 15, 2023, 7:00 - 8:30 PM. IN PERSON TALK.
Title:     EILC toposes.

Abstract: In topos theory, local connectedness of a geometric morphism is a very geometric property, in the sense that it is stable under base change, can be checked locally, and so on. In some situations however, the weaker property of being essential is easier to verify. In this talk, we will discuss EILC toposes: toposes E such that any essential geometric morphism with codomain E is automatically locally connected. It turns out that many toposes of interest are EILC, including toposes of sheaves on Hausdorff spaces and classifying toposes of compact groups.



- - - - Thursday, Mar 16, 2023 - - - -



- - - - Friday, Mar 17, 2023 - - - -

Set Theory Seminar
CUNY Graduate Center
Friday, March 17, 12:15pm NY time
Virtual: Please email Victoria Gitman (vgitman@gmail.com) for meeting id.
Jonathan Osinski, University of Hamburg


Logic Workshop
CUNY Graduate Center
Modality TBA
Friday March 17, 2:00pm-3:30pm, Room 6417
Filippo Calderoni, Rutgers University


- - - - Other Logic News - - - -


- - - - Web Site - - - -

Find us on the web at:  nylogic.github.io
(site designed, built & maintained by Victoria Gitman)

--------  ADMINISTRIVIA  --------

To subscribe/unsubscribe to this list, please email your request to jreitz@nylogic.org.

If you have a logic-related event that you would like included in future mailings, please email jreitz@nylogic.org

Barcelona Set Theory Seminar

Barcelona Logic Seminar

Dear All, 
Please find attached the announcement of the next Barcelona Set Theory Seminar session.

SPEAKER: Radek Honzik
TITLE: Compactness principles at small cardinals and their preservation
DATE: Wednesday, 8 March 2023
TIME: 16:00 (CET)
PLACE: Room B1 (UB). The Seminar can also be followed online via Zoom:


Best regards,
Joan

P.S.: If you do not wish to receive any more announcements, please send an email to bagaria@ub.edu with the text “Unsubscribe”.






Joan Bagaria 
ICREA Research Professor 
Universitat de Barcelona
Departament de Matemàtiques i Informàtica
Gran Via de les Corts Catalanes 585
08007 Barcelona
Catalonia 

Phone: +34 93 402 1609
joan.bagaria@icrea.cat
bagaria@ub.edu


Wednesday seminar

Prague Set Theory Seminar
Dear all, The seminar meets on Wednesday March 8th at 11:00 in the Institute of Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building. Program: Chris Lambie-Hanson -- Topics in cardinal arithmetic We will discuss some recent results and some not-so-recent results in cardinal arithmetic and PCF theory. The precise topics will depend on the interests of the audience and the preparedness of the speaker but may include: existence theorems about PCF-theoretic scales, Silver's theorem for pseudopowers, the cov vs. pp problem, or recent work of the speaker showing that a generalized narrow system property implies Shelah's Strong Hypothesis. Best, David

(KGRC) two talks at U Wien and TU Wien

Kurt Godel Research Center
The KGRC welcomes as guests: Martin Hils (host: Matthias Aschenbrenner) visits the KGRC until March 31. Clifton Ealy (host: Matthias Aschenbrenner) visits the KGRC until August 15. Juris Steprāns (host: Vera Fischer) visits the KGRC from March 6 to March 10 and gives a talk, see below. Lou van den Dries (host: Matthias Aschenbrenner) visits the KGRC from March 10 to March 22. Silvain Rideau-Kikuchi (host: Matthias Aschenbrenner) visits the KGRC from March 15 to March 20 and gives a talk, details to be announced at a later time. * * * Set Theory Research Seminar Kurt Gödel Research Center Tuesday, March 7 "Selective and Milliken-Taylor ultrafilters" Juris Steprāns (York U, CA) I will report on joint work with Dilip Raghavan solving a question of Blass about whether the existence of many selective ultrafilters implies the existence of Milliken-Taylor ultrafilters. The first part of the talk will provide the historical context of what was known in the mid 80s that prompted Blass to ask his question. The second part will discuss the key technical advance in our argument. Time and Place Talk at 3:00pm Universität Wien Institut für Mathematik Kolingasse 14-16 1090 Wien 1st floor Seminar room 10 Please direct any questions about this talk to vera.fischer@univie.ac.at. * * * FG1 Seminar Algebra Research Unit Wednesday, March 8 "Various ways to compare spaces, subsets, and functions" Raphaël Carroy (Università degli Studi di Torino, IT) One can consider a quasi-order like topological embeddability when one wants to compare a Polish (or analytic) space to another. If instead one tries to rank the complexities emerging among subsets of a given space, continuous reducibility becomes relevant. Both these quasi-orders have extensions to functions between Polish (or analytic) spaces. Some natural questions about these quasi-orders are then: the existence of simple bases, characterizing the simplicity or complexity of the quasi-order in itself, and describing it when it turns out to be simple enough. I will try to give some context on these quasi-orders and review known and more recent results and applications. Times and Places Snacks and beverages at 2:00pm Institute of Discrete Mathematics and Geometry TU Wien Wiedner Hauptstrasse 8-10 1040 Wien Austria 5th floor, green part room Besprechungsraum DA 05 C22 Talk at 2:45pm Institute of Discrete Mathematics and Geometry TU Wien Wiedner Hauptstrasse 8-10 1040 Wien Austria 8th floor, green part room Dissertantenraum DA 08 B19 Please direct any questions about this talk to sandra.mueller@tuwien.ac.at.

CosmoCaixa Barcelona: Joel Hamkins: pensament estratègic en jocs infinits

Barcelona Logic Seminar
Benvolguts,
us envio l’anunci de la conferència que farà Joel Hamkins al Cosmocaixa el dia 16 de març a les 7. L’entrada val 6 Euros, però us puc donar un codi que la redueix a 3. Inclou la visita al Cosmocaixa.

Joel Hamkins: pensament estratègic en jocs infinits 

https://cosmocaixa.org/ca/p/pensament-estrategic-en-jocs-infinits_a122155152 . 

Espero que vingueu,
Joan


Dear All,
here is the announcement of the talk by Joel Hamkins he will give at Cosmocaixa (Science Museum in Barcelona) on March 16, 7pm. The entry fee is 6 Euros, but I can give you a code that reduces it to 3 Euros. It includes the entrance to the museum
  
Joel Hamkins: Strategic Thinking in Infinite Games

https://cosmocaixa.org/ca/p/pensament-estrategic-en-jocs-infinits_a122155152 . 

Hope to see you there!
Joan



Joan Bagaria 
ICREA Research Professor 
Universitat de Barcelona
Departament de Matemàtiques i Informàtica
Gran Via de les Corts Catalanes 585
08007 Barcelona
Catalonia 

Phone: +34 93 402 1609
joan.bagaria@icrea.cat
bagaria@ub.edu


Logic Seminar 8 March 2023 17:00 hrs at NUS by Chong Chitat

NUS Logic Seminar
Invitation to the Logic Seminar at the National University of Singapore Date: Wednesday, 8 March 2023, 17:00 hrs Place: NUS, Department of Mathematics, S17#05-11 Speaker: Chong Chitat, National University of Singapore Title: Proof-theoreitic strength of the Halpern-Lauchli Theorem URL: http://www.comp.nus.edu.sg/~fstephan/logicseminar.html Abstract: Let T be the full infinite binary tree (i.e. the Cantor space). An infinite subtree S of T is a strong subtree if (i) S is isomorphic to T, (ii) if sigma is a node in S, and sigma_0, sigma_1 are its immediate successors in S, then sigma_0 and sigma_1 have the same length in T and furthermore (iii) the intersection of sigma_0 and sigma_1 is sigma. The Halpern-Lauchli Theorem is a theorem in combinatorial mathematics which states that for any finite number of infinite full binary trees T_1,T_2,..., T_d, and any finite coloring of the d-row vectors in T_1 x T_2 x ... x T_d, there exist strong subtrees S_1 subseteq T_1, S_2 subseteq T_2, ..., S_d subseteq T_d for which all d-row vectors in S_1 x S_2 x ... x S_d have the same color. This Ramsey type theorem is yet another striking demonstration of the existence of order within chaotic disorder. There is no known simple proof of this theorem in the published literature. In this talk we discuss the proof-theoretic strength of the Halpern-Lauchli theorem from the reverse mathematics point of view. In particular, we give a characterisation of the inductive strength of this theorem as well as its conservation strength over a base theory weaker than Sigma_2-induction. This is joint work with Li Wei and Yang Yue.

Today's Logic Seminar is via Zoom

NUS Logic Seminar
Hello, please note that today's talk is by Zoom and there is no physical meeting. Here again the login info: Return-Path: Date: Fri, 24 Feb 2023 15:00:41 +0800 From: Frank STEPHAN To: matyangy@nus.edu.sg, settheorytalks@gmail.com, belanger@nus.edu.sg, Subject: Logic Seminar 1 March 2023 17:00 hrs Singapore time by Linus Richter Invitation to the Logic Seminar at the National University of Singapore Date: Wednesday, 1 March 2023, 17:00 hrs Place: NUS, Department of Mathematics, Talk via Zoom: https://nus-sg.zoom.us/j/83049258042?pwd=UWViaWNvTFUrdFdhOHJCdEVydnVkdz09 Meeting ID: 830 4925 8042 Passcode: 1729=x3+y3 Speaker: Linus Richter, Victoria University of Wellington Title: Co-analytic Counterexamples to Marstrand's Projection Theorem Abstract: A recent "point-to-set principle" of Jack Lutz and Neil Lutz characterises the Hausdorff dimension of any subset of Euclidean space in terms of the Kolmogorov complexity of its individual points. Sets with particular fractal properties can now be constructed point-by-point, by coding "enough" information into each point, bit-by-bit. After introducing the point-to-set principle, I will present a new result in fractal geometry: under V=L (the axiom of constructiblity), I will outline the construction of co-analytic sets of Euclidean space which fail Marstrand's Projection Theorem, a classical result in fractal geometry concerning the dimension of orthogonal projections of analytic plane sets onto lines. URL: http://www.comp.nus.edu.sg/~fstephan/logicseminar.html

Nankai Logic Colloquium

Nankai Logic Colloquium

Hello everyone,


This week our weekly Nankai Logic Colloquium is going to be in the afternoon.


Our speaker this week will be Martino Lupini from the University of Bologna. This talk is going to take place this Friday, Mar. 03,  from 16:00 to 17:00 (UTC+8, Beijing time). 


Title: Definable refinements of classical algebraic invariants

Abstract: In this talk I will explain how methods from logic allow one to construct refinements of classical algebraic invariants that are endowed with additional topological and descriptive set-theoretic information. This approach brings to fruition initial insights due to Eilenberg, Mac Lane, and Moore (among others) with the additional ingredient of recent advanced tools from logic. I will then present applications of this viewpoint to invariants from a number of areas in mathematics, including operator algebras, group theory, algebraic topology, and homological algebra.

___________________________________________________________________________________________________________________________________________________


This is going to be an online event. Follow the link below to join the Zoom meeting. Please use your real name to join the meeting.

Title:                The 18th Nankai Logic Colloquium --Martino Lupini

Time:                16:00, Mar. 3, 2023 (Beijing Time)

Zoom Number:859 1679 0296

Passcode:         577088

Link:                 https://zoom.us/j/85916790296?pwd=WGRrZjJKa0kvRE9KSGtxNkJia2JiUT09

_____________________________________________________________________


Best wishes,

Ming Xiao




Cross-Alps Logic Seminar (speaker: Dugald MacPherson)

Cross-Alps Logic Seminar
On Friday 03.03.2023 at 16.00
Dugald MacPherson (University of Leeds)
will give a talk on 
Uniform families of definable sets in finite structures

Please refer to the usual webpage of our LogicGroup for more details and the abstract of the talk.
The seminar will be held remotely through Webex. Please write to vincenzo.dimonte [at] uniud [dot] it for the link to the event.

The Cross-Alps Logic Seminar is co-organized by the logic groups of Genoa, Lausanne, Turin and Udine as part of our collaboration in the project PRIN 2017 'Mathematical logic: models, sets, computability'.

All the best,
Vincenzo

(KGRC) Logic Colloquium talk on Thursday, March 2

Kurt Godel Research Center
The KGRC welcomes as guests: Martin Hils (host: Matthias Aschenbrenner) visits the KGRC until March 31. Clifton Ealy (host: Matthias Aschenbrenner) visits the KGRC until August 15. Jerzy Kąkol (host: Damian Sobota) visits the KGRC until March 3. Manuel López Pellicer (host: Damian Sobota) visits the KGRC until March 3. Katrin Tent (host: Matthias Aschenbrenner) visits the KGRC from March 1 to March 5 and gives a talk (see below). Juris Steprāns (host: Vera Fischer) visits the KGRC from March 6 to March 10 and gives a talk, details to be announced at a later time. Silvain Rideau-Kikuchi (host: Matthias Aschenbrenner) visits the KGRC from March 15 to March 20 and gives a talk, details to be announced at a later time. * * * Logic Colloquium Kurt Gödel Research Center Thursday, March 2 "Simplicity of automorphism groups of homogeneous structures" Katrin Tent (Universität Münster, DE) We discuss some general criteria that can be used to show that the automorphism group of a homogeneous structure (such as metric space, right-angled building, graph or hypergraphs) are simple groups or have simple quotients. Time and Place Talk at 3:00pm Universität Wien Institut für Mathematik Oskar-Morgenstern-Platz 1 1090 Wien 2nd floor room HS 11 If you would like to follow the talk online, please let Matthias Aschenbrenner (matthias.aschenbrenner@univie.ac.at) or Vera Fischer (vera.fischer@univie.ac.at) know in advance and we will arrange for it to be streamed.

Wednesday seminar

Prague Set Theory Seminar
Dear all, The seminar meets on Wednesday March 1st at 11:00 in the Institute of Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building. The program is not yet determined. If anybody is interested in speaking or to hear something specific, do let me know. Best, David

This Week in Logic at CUNY

This Week in Logic at CUNY
This Week in Logic at CUNY:

- - - - Monday, Feb 27, 2023 - - - -

Rutgers Logic Seminar 
Monday, February 27, 2pm, Rutgers University, Hill 005
Leonardo Nagami Coregliano, IAS Princeton
Ramsey's Theorem in the countable and weak randomness


Logic and Metaphysics Workshop
Date: Monday, February 27, 4.15-6.15pm (NY time), GC 9205
NOTE: Meetings this semester are in person only (no zoom)
For meeting information, please sign up for our mailing list at https://logic.commons.gc.cuny.edu/about/
Lionel Shapiro, UConn
Title: Neopragmatism and logic: A deflationary proposal

Abstract: Neopragmatists seek to sidestep metaphysical puzzles by shifting the target of philosophical explanation from the objects we think and talk about to the functions of expressions and concepts in our cognitive economy. Logical vocabulary can serve as a target for neopragmatist inquiry, and it has also posed obstacles to neopragmatist accounts of other vocabulary. I will argue that the obstacles can be addressed by adopting a neopragmatist perspective toward logical relations, such as logical consequence, and toward propositional content. Doing so calls into question two purported constraints on explanations of the functions of logical connectives. I will sketch an account made possible by rejecting those constraints, one according to which logical connectives serve to express dialectical attitudes. The proposal is deflationary in two ways: it rests on an extension of deflationism from truth to logical relations, and it aims to deflate some of neopragmatists’ theoretical ambitions.

 


- - - - Tuesday, Feb 28, 2023 - - - -

Models of Peano Arithmetic (MOPA)
Tuesday, February 28, 1:00pm
Virtual (email Victoria Gitman vgitman@gmail.com for meeting id)

Zuzana Hanikova, Czech Academy of Sciences
Vopěnka's Alternative Set Theory and its mathematical context

Vopěnka first presented his Alternative Set Theory (AST) in the monograph 'Mathematics in the Alternative Set Theory' published by Teubner, Leipzig in 1979. Another book presenting the theory, 'Introduction to Mathematics in the Alternative Set Theory', was published in 1989 in Slovak by Alfa, Bratislava. In addition there are numerous journal papers on the AST by members of the research group established by Vopěnka, and the proceedings of a conference dedicated to the AST, also from 1989. In several essays, Vopěnka sought to lay out the motivation and philosophical import of the AST and some of his subsequent work. As one consequence of the emphasis on his philosophy, the mathematical inspiration for the AST has been somewhat obliterated. The aim of the talk is to discuss the design choices Vopěnka made for the AST in relation to pertinent mathematical developments of the 20th century, such as Skolem's work on nonstandard models of arithmetic, Robinson's nonstandard analysis, Rieger's nonstandard models of arithmetic, Vopěnka's nonstandard model of set theory, Vopěnka and Hájek's theory of semisets, or Parikh's almost consistent theories. The presentation will include an outline of the AST following the works of Vopěnka and Sochor. This is a historical talk; no new mathematical results on the AST will be presented.




- - - - Wednesday, Mar 1, 2023 - - - -



- - - - Thursday, Mar 2, 2023 - - - -



- - - - Friday, Mar 3, 2023 - - - -




Next Week in Logic at CUNY:

- - - - Monday, Mar 6, 2023 - - - -

Rutgers Logic Seminar 
Monday, March 6, 2pm, Rutgers University, Hill 005
Will Adkisson, UIC


Logic and Metaphysics Workshop
Date: Monday, March 6, 4.15-6.15pm (NY time), GC 9205
NOTE: Meetings this semester are in person only (no zoom)
For meeting information, please sign up for our mailing list at https://logic.commons.gc.cuny.edu/about/
Gary Ostertag (CUNY/Mount Sinai)

Title: Lewis on accommodation and representation de re

Abstract: Recall Lumpl, the lump of clay out of which the statue Goliath is fashioned. While (1) ‘Lumpl could have survived a squashing’ is true, (2) ‘Goliath could have survived a squashing’ is false, it being after all essential to Goliath, but not to Lumpl, that it be a statue. We have here an example of what David Lewis (1986) called “the inconstancy of representation de re”. For Lewis, the inconstancy does not amount to inconsistency, but rather points to the context-sensitivity of de re modal predication: (1) and (2) make implicit, context-sensitive reference to different counterpart relations. Once we recognize this, Lewisians argue, it becomes clear how our intuitive truth-conditional judgments are fully consistent. As I show, however, the conversational rule that triggers the implicit reference not only fails to license the reference shift, it effectively prohibits it. The upshot is that counterpart theory is deprived of a central motivation.

 



- - - - Tuesday, Mar 7, 2023 - - - -

Models of Peano Arithmetic (MOPA)
Tuesday, March 7, 1:00pm
Virtual (email Victoria Gitman vgitman@gmail.com for meeting id)

Bellaouar Djamel, University 08 Mai 1945 Guelma
Some generalizations on the representation of unlimited natural numbers

Based on permanence principles of nonstandard analysis and as a continuation of the papers [1-3], we present some notes and questions on the representation of unlimited natural numbers. As a natural generalization, let  be an unlimited  by  matrix with integer entries (i.e one of its integer entries is unlimited). Here we prove that every unlimited matrix  with integer entries can be written as the sum of a limited matrix S with integer entries and the product of two unlimited matrices  and  with integer entries, that is, . For further research, we propose several matrix representation forms.

Finally, we consider the numbers of the form  where , are integers, which are called Gaussian integers. In the case when  or  is unlimited, the number  is said to be unlimited. Also, some notes on the representation of unlimited Gaussian integers are given.

[1] A. Boudaoud, La conjecture de Dickson et classes particulière d'entiers, Ann. Math. Blaise Pascal. 13 (2006), 103-109.
[2] A. Boudaoud and D. Bellaouar, Representation of integers: A nonclassical point of view, J. Log. Anal. 12:4 (2020) 1-31.
[3] K. Hrbacek, On Factoring of unlimited integers, J. Log. Anal. 12:5 (2020) 1-6.




- - - - Wednesday, Mar 8, 2023 - - - -



- - - - Thursday, Mar 9, 2023 - - - -



- - - - Friday, Mar 10, 2023 - - - -

Logic Workshop
CUNY Graduate Center
Modality TBA
Friday March 10, 2:00pm-3:30pm, Room 6417
Thilo Weinert, University of Vienna


Set Theory Seminar
CUNY Graduate Center
Friday, March 10, 12:15pm NY time
Virtual: Please email Victoria Gitman (vgitman@gmail.com) for meeting id.
James Holland, Rutgers University



- - - - Other Logic News - - - -


- - - - Web Site - - - -

Find us on the web at:  nylogic.github.io
(site designed, built & maintained by Victoria Gitman)

--------  ADMINISTRIVIA  --------

To subscribe/unsubscribe to this list, please email your request to jreitz@nylogic.org.

If you have a logic-related event that you would like included in future mailings, please email jreitz@nylogic.org

Barcelona Set Theory Seminar

Barcelona Logic Seminar

Dear All, 
Please find attached the announcement of the next Barcelona Set Theory Seminar session.

SPEAKER: Boriša Kuzeljević
TITLE: Lower bounds of sets of P-points
DATE: Wednesday, 29 February 2023
TIME: 16:00 (CET)
PLACE: Room B1 (UB). The Seminar can also be followed online via Zoom:


Best regards,
Joan

P.S.: If you do not wish to receive any more announcements, please send an email to bagaria@ub.edu with the text “Unsubscribe”.






Joan Bagaria 
ICREA Research Professor 
Universitat de Barcelona
Departament de Matemàtiques i Informàtica
Gran Via de les Corts Catalanes 585
08007 Barcelona
Catalonia 

Phone: +34 93 402 1609
joan.bagaria@icrea.cat
bagaria@ub.edu


BLAST in Charlottle NC: May 16-20, 2023

Conference
We would like to bring your attention to the upcoming BLAST 2023 conference, which will take place at the University of North Carolina, Charlotte, from May 16 - 20. BLAST is a conference series focusing on Boolean Algebras, Lattices, Universal Algebra and Model Theory, Set Theory, and Topology. We hope that you will be able to attend the conference, and to contribute a talk. The confirmed invited speakers for the conference are: - Marco Abbadini, University of Salerno - Dana Bartošová, University of Florida - William Chan, University of North Texas - Daniel Herden, Baylor University - Andre Kornell, Dalhousie University - David Stanovský, Charles University Additionally, we can confirm that a tutorial will be given by - Keith Kearnes, University of Colorado Boulder The website for this conference is still under construction, but a preliminary version can be found here: https://pages.charlotte.edu/blast2023/. The home website for the BLAST conference series can be found here: https://math.colorado.edu/blast/. Some financial support, provided by the National Science Foundation, is available for students and young researchers.
Link to more info

CMU Math Logic Seminar next Tuesday

Carnegie Mellon Logic Seminar
TUESDAY, February 28, 2023

Mathematical Logic Seminar:  3:30-4:30 PM Eastern, Online, Marcin Sabok, McGill University

Join Zoom Meeting: https://cmu.zoom.us/j/92655324096?pwd=VUhSSlkrdHMxbTlSYUMxYzFXM01kdz09
Meeting ID: 926 5532 4096
Passcode: 555455

TITLE: Perfect matchings in hyperfinite graphings

ABSTRACT: The talk will focus on recent results on measurable perfect matchings in hyperfinite graphings. In particular, we will discuss a result saying that every regular hyperfinite one-ended bipartite graphing admits a measurable perfect matching. We will also see some applications of these results, answering several questions in the field. For instance we will characterize the existence of factor of iid perfect matchings in bipartite Cayley graphs, extending a result of Lyons and Nazarov. We will also answer a question of Bencs, Hruskova and Toth arising in the study of balanced orientations in graphings. Finally, we see how the results imply the measurable circle squaring. This is joint work with Matt Bowen and Gabor Kun.

Logic Seminar 1 March 2023 17:00 hrs Singapore time by Linus Richter at NUS via Zoom

NUS Logic Seminar
Invitation to the Logic Seminar at the National University of Singapore Date: Wednesday, 1 March 2023, 17:00 hrs Place: NUS, Department of Mathematics, Talk via Zoom: https://nus-sg.zoom.us/j/83049258042?pwd=UWViaWNvTFUrdFdhOHJCdEVydnVkdz09 Meeting ID: 830 4925 8042 Passcode: 1729=x3+y3 Speaker: Linus Richter, Victoria University of Wellington Title: Co-analytic Counterexamples to Marstrand's Projection Theorem Abstract: A recent "point-to-set principle" of Jack Lutz and Neil Lutz characterises the Hausdorff dimension of any subset of Euclidean space in terms of the Kolmogorov complexity of its individual points. Sets with particular fractal properties can now be constructed point-by-point, by coding "enough" information into each point, bit-by-bit. After introducing the point-to-set principle, I will present a new result in fractal geometry: under V=L (the axiom of constructiblity), I will outline the construction of co-analytic sets of Euclidean space which fail Marstrand's Projection Theorem, a classical result in fractal geometry concerning the dimension of orthogonal projections of analytic plane sets onto lines. URL: http://www.comp.nus.edu.sg/~fstephan/logicseminar.html

Nankai Logic Colloquium

Nankai Logic Colloquium

Hello everyone,


This week our weekly Nankai Logic Colloquium is going to be in the morning.


Our speaker this week will be Slawomir Solecki from Cornell University. This talk is going to take place this Friday, Feb.24, 2023,  from 9am to 10am (UTC+8, Beijing time). 

Title: Descriptive Set Theory and closed groups generated by generic measure preserving transformations

Abstract: The subject matter of the talk lies within the area that employs the descriptive set theoretic point of view in the study of large topological groups. 

The behavior of a measure preserving transformation, even a generic one, is highly non-uniform. In contrast to this observation, a different picture of a very uniform behavior of the closed group generated by a generic measure preserving transformation $T$ has emerged. This picture included substantial evidence that pointed to these groups (for a generic $T$) being all topologically isomorphic to a single group, namely, $L^0$---the topological group of all Lebesgue measurable functions from $[0,1]$ to the circle. In fact, Glasner and Weiss asked if this is the case.

We will describe the background touched on above, including the descriptive set theoretic background. We will indicate a proof of the following theorem that answers the Glasner--Weiss question in the negative: for a generic measure preserving transformation $T$, the closed group generated by $T$ is {\bf not} topologically isomorphic to $L^0$.

____________________________________________________________________________________________________________________________________

This is going to be an online event. Follow the link below to join the Zoom meeting. Please use your real name to join the meeting.

Title:                 The 17th Nankai Logic Colloquium --Slawomir Solecki

Time:                9:00am, Feb. 24, 2023 (Beijing Time)

Zoom Number:854 3647 9165

Passcode:         977845

Link:                 https://zoom.us/j/85436479165?pwd=cjFwZlpUZWtCcnhTci9OK0R5ODU0UT09

_____________________________________________________________________


Best wishes,

Ming Xiao




This Week in Logic at CUNY

This Week in Logic at CUNY
This Week in Logic at CUNY:

- - - - Monday, Feb 13, 2023 - - - -

Rutgers Logic Seminar 
Monday, February 13, 2pm, Rutgers University, Hill 005
James Holland, Rutgers
Forcing more choice over the Chang model


- - - - Tuesday, Feb 14, 2023 - - - -

Models of Peano Arithmetic (MOPA)
Tuesday, February 14, 1:00pm
Virtual (email Victoria Gitman vgitman@gmail.com for meeting id)

Vladimir Kanovei, Institute for Information Transmission Problems
On the significance of parameters in the choice and сomprehension schemata in the 2nd-order Peano arithmetic

Parameters are free variables in various axiom schemata in PA, ZFC, and other similar theories. Given an axiom schema S, we let S* be the parameter-free sub-schema.

Kreisel (A survey of proof theory, JSL 1968) was one of those who paid attention to the comparison of some schemata in second-order PA and their parameter-free versions. In particular, Kreisel noted that

[...] if one is convinced of the significance of something like a given axiom schema, it is natural to study details, such as the effect of parameters.

This talk is devoted to the effect of parameters in the schemata of Comprehension and Choice in second-order arithmetic.




- - - - Wednesday, Feb 15, 2023 - - - -

The New York City Category Theory Seminar
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York

Special Topic:    TQFT and ComputationSecond Lecture.

Speaker:     Mee Seong Im, United States Naval Academy, Annapolis.

Date and Time:     Wednesday February 15, 2023, 7:00 - 8:30 PM. IN PERSON TALK.

Title:     Automata and topological theories.


Abstract: Theory of regular languages and finite state automata is part of the foundations of computer science. Topological quantum field theories (TQFT) are a key structure in modern mathematical physics. We will interpret a nondeterministic automaton as a Boolean-valued one-dimensional TQFT with defects labelled by letters of the alphabet for the automaton. We will also describe how a pair of a regular language and a circular regular language gives rise to a lax one-dimensional TQFT.




- - - - Thursday, Feb 16, 2023 - - - -



- - - - Friday, Feb 17, 2023 - - - -

Logic Workshop
CUNY Graduate Center
Hybrid: Please email Victoria Gitman (vgitman@gmail.com) for meeting id.
Friday February 17, 2:00pm-3:30pm, Room 6417

Russell Miller, CUNY
Computability and the Absolute Galois Group of 

Fix a computable presentation  of the algebraic closure of the rational numbers. The absolute Galois group of the rational numbers, which is precisely the automorphism group of the field , may then be viewed as a collection of paths through a finite-branching tree. Each individual automorphism has a Turing degree. We will use known results in computability to try to build natural countable elementary subgroups of the absolute Galois group. Several intriguing questions in number theory will appear as we measure the extent to which we succeed in doing so.



Next Week in Logic at CUNY:

- - - - Monday, Feb 20, 2023 - - - -



- - - - Tuesday, Feb 21, 2023 - - - -

Models of Peano Arithmetic (MOPA)
Tuesday, February 21, 1:00pm
Virtual (email Victoria Gitman vgitman@gmail.com for meeting id)

Alexei Miasnikov, Stevens Institute of Technology
First-order classification and non-standard models

In this talk I will discuss some recent advances in the first-order classification problem. I will touch on first-order rigidity and quasi finite axiomatization. However, the main point of the presentation is on how, in principle, one can describe all structures which are first-order equivalent to a given one. This leads to non-standard models of algebraic structures (aka non-standard analysis or non-standard arithmetic), which are interesting in their own right.




- - - - Wednesday, Feb 22, 2023 - - - -

The New York City Category Theory Seminar
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York

Special Topic:    TQFT and ComputationThird Lecture.
Speaker:     Joshua Sussan, CUNY.
Date and Time:     Wednesday February 22, 2023, 7:00 - 8:30 PM. IN PERSON TALK.
Title:     Non-semisimple Hermitian TQFTs.

Abstract: Topological quantum field theories coming from semisimple categories build upon interesting structures in representation theory and have important applications in low dimensional topology and physics. The construction of non-semisimple TQFTs is more recent and they shed new light on questions that seem to be inaccessible using their semisimple relatives. In order to have potential applications to physics, these non-semisimple categories and TQFTs should possess Hermitian structures. We will define these structures and give some applications.




- - - - Thursday, Feb 23, 2023 - - - -



- - - - Friday, Feb 24, 2023 - - - -

Logic Workshop
CUNY Graduate Center
Hybrid: Please email Victoria Gitman (vgitman@gmail.com) for meeting id.
Friday February 24, 2:00pm-3:30pm, Room 6417
Johanna Franklin, Hofstra University

When Gromov asked 'What is a typical group?', he was thinking of finitely presented groups, and he proposed an approach involving limiting density. Here, we reframe this question in the context of universal algebra and discuss some examples illustrating the behaviors of some of these algebraic varieties and then general conditions that imply some of these behaviors. Our primary general result states that for a commutative generalized bijective variety and presentations with a single generator and single identity, the zero-one law holds and, furthermore, that the sentences with density 1 are those true in the free structure. The proof of this result requires a specialized version of Gaifman's Locality Theorem that enables us to get a better bound on the complexity of the formulas of interest to us.

This work is joint with Meng-Che 'Turbo' Ho and Julia Knight.




Next Week in Logic at CUNY:

- - - - Monday, Feb 27, 2023 - - - -

Logic and Metaphysics Workshop
Date: Monday, February 27, 4.15-6.15pm (NY time), GC room TBD
NOTE: Meetings this semester are in person only (no zoom)
For meeting information, please sign up for our mailing list at https://logic.commons.gc.cuny.edu/about/
Lionel Shapiro, UConn



- - - - Tuesday, Feb 28, 2023 - - - -

Models of Peano Arithmetic (MOPA)
Tuesday, February 28, 1:00pm
Virtual (email Victoria Gitman vgitman@gmail.com for meeting id)

Zuzana Hanikova, Czech Academy of Sciences
Vopěnka's Alternative Set Theory and its mathematical context

Vopěnka first presented his Alternative Set Theory (AST) in the monograph 'Mathematics in the Alternative Set Theory' published by Teubner, Leipzig in 1979. Another book presenting the theory, 'Introduction to Mathematics in the Alternative Set Theory', was published in 1989 in Slovak by Alfa, Bratislava. In addition there are numerous journal papers on the AST by members of the research group established by Vopěnka, and the proceedings of a conference dedicated to the AST, also from 1989. In several essays, Vopěnka sought to lay out the motivation and philosophical import of the AST and some of his subsequent work. As one consequence of the emphasis on his philosophy, the mathematical inspiration for the AST has been somewhat obliterated. The aim of the talk is to discuss the design choices Vopěnka made for the AST in relation to pertinent mathematical developments of the 20th century, such as Skolem's work on nonstandard models of arithmetic, Robinson's nonstandard analysis, Rieger's nonstandard models of arithmetic, Vopěnka's nonstandard model of set theory, Vopěnka and Hájek's theory of semisets, or Parikh's almost consistent theories. The presentation will include an outline of the AST following the works of Vopěnka and Sochor. This is a historical talk; no new mathematical results on the AST will be presented.




- - - - Wednesday, Mar 1, 2023 - - - -



- - - - Thursday, Mar 2, 2023 - - - -



- - - - Friday, Mar 3, 2023 - - - -




- - - - Other Logic News - - - -


- - - - Web Site - - - -

Find us on the web at:  nylogic.github.io
(site designed, built & maintained by Victoria Gitman)

--------  ADMINISTRIVIA  --------

To subscribe/unsubscribe to this list, please email your request to jreitz@nylogic.org.

If you have a logic-related event that you would like included in future mailings, please email jreitz@nylogic.org

Wednesday seminar

Prague Set Theory Seminar
Dear all, The seminar meets on Wednesday February 22nd at 11:00 in the Institute of Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building. Program: Jonathan Cancino Manriquez -- Maximal trees on P(omega)/fin Given a partial order (P,<), a tree T on P is a subset of P such that T order by the inverse order defined by <, is a tree. This notion was introduced by D. Monk some years ago, and asked about the size of maximal trees on [omega]^omega order by almost inclusion. In this talk we will review some constructions of maximal trees of cardinality omega_1 under some parametrized diamond principles and some related results. This is joint work with G. Campero, M. Hrusak and F. Miranda. Best, David

Barcelona Set Theory Seminar

Barcelona Logic Seminar

Dear All, 
Please find attached the announcement of the next Barcelona Set Theory Seminar session.

SPEAKER:  On Disjoint Stationary Sequences
DATE: Wednesday, 22 February 2023
TIME: 16:00 (CET)
PLACE: Room B1 (UB). The Seminar can also be followed online via Zoom:


Best regards,
Joan

P.S.: If you do not wish to receive any more announcements, please send an email to bagaria@ub.edu with the text “Unsubscribe”.



Joan Bagaria 
ICREA Research Professor 
Universitat de Barcelona
Departament de Matemàtiques i Informàtica
Gran Via de les Corts Catalanes 585
08007 Barcelona
Catalonia 

Phone: +34 93 402 1609
joan.bagaria@icrea.cat
bagaria@ub.edu


Logic Seminar Wed 15 Feb 2023 17:00 hrs at NUS by David Belanger

NUS Logic Seminar
Invitation to the Logic Seminar at the National University of Singapore Date: Wednesday, 15 February 2023, 17:00 hrs Place: NUS, Department of Mathematics, S17#05-11 Speaker: David Belanger Title: A system of functionals-of-finite-type for BSigma_n models Abstract: We present a system of functionals that can serve as Skolem functions, so that any arithmetical formula can be rewritten in terms of them, in a model of BSigma_n + not ISigma_n. A distinguishing feature of our construction is that each functional is coded as a natural number within the model, and there is an upper bound on the codes. The method has a number of interesting applications. This is joint work with Chong, Li, Wong and Yang. URL: http://www.comp.nus.edu.sg/~fstephan/logicseminar.html

Nankai Logic Colloquium

Nankai Logic Colloquium

Hello everyone,


This week our weekly Nankai Logic Colloquium is going to be in the afternoon.


Our speaker this week will be Riccardo Camerlo from University of Genoa. This talk is going to take place this Friday, Feb.17, 2023,  from 4 pm to 5 pm (UTC+8, Beijing time). 

Title: On some reducibility hierarchies

Abstract:
The notion of reducibility allows to compare sets or, more generally,  
relations by using a given class of functions to make the comparison.  
The choice of different classes of functions may give rise to very  
diffent hierarchies.
Purpose of the talk is to give an elementary presentation of some of  
these hierarchies, discuss some examples, and comment on some open  
problems.

___________________________________________________________________________________________________________________________________________________

This is going to be an online event. Follow the link below to join the Zoom meeting. Please use your real name to join the meeting.

Title:                 The 16th Nankai Logic Colloquium --Riccardo Camerlo

Time:                16:00pm, Feb. 17, 2023 (Beijing Time)

Zoom Number:839 6396 1742

Passcode:        321054

Link:                 https://zoom.us/j/83963961742?pwd=c2ppSXpMQks3Vit5bnZkUm5heElNUT09

_____________________________________________________________________


Best wishes,

Ming Xiao




This Week in Logic at CUNY

This Week in Logic at CUNY
This Week in Logic at CUNY:

- - - - Monday, Feb 13, 2023 - - - -

Rutgers Logic Seminar 
Monday, February 13, 2pm, Rutgers University, Hill 005
James Holland, Rutgers
Forcing more choice over the Chang model


- - - - Tuesday, Feb 14, 2023 - - - -

Models of Peano Arithmetic (MOPA)
Tuesday, February 14, 1:00pm
Virtual (email Victoria Gitman vgitman@gmail.com for meeting id)

Vladimir Kanovei, Institute for Information Transmission Problems
On the significance of parameters in the choice and сomprehension schemata in the 2nd-order Peano arithmetic

Parameters are free variables in various axiom schemata in PA, ZFC, and other similar theories. Given an axiom schema S, we let S* be the parameter-free sub-schema.

Kreisel (A survey of proof theory, JSL 1968) was one of those who paid attention to the comparison of some schemata in second-order PA and their parameter-free versions. In particular, Kreisel noted that

[...] if one is convinced of the significance of something like a given axiom schema, it is natural to study details, such as the effect of parameters.

This talk is devoted to the effect of parameters in the schemata of Comprehension and Choice in second-order arithmetic.




- - - - Wednesday, Feb 15, 2023 - - - -

The New York City Category Theory Seminar
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York

Special Topic:    TQFT and ComputationSecond Lecture.

Speaker:     Mee Seong Im, United States Naval Academy, Annapolis.

Date and Time:     Wednesday February 15, 2023, 7:00 - 8:30 PM. IN PERSON TALK.

Title:     Automata and topological theories.


Abstract: Theory of regular languages and finite state automata is part of the foundations of computer science. Topological quantum field theories (TQFT) are a key structure in modern mathematical physics. We will interpret a nondeterministic automaton as a Boolean-valued one-dimensional TQFT with defects labelled by letters of the alphabet for the automaton. We will also describe how a pair of a regular language and a circular regular language gives rise to a lax one-dimensional TQFT.




- - - - Thursday, Feb 16, 2023 - - - -



- - - - Friday, Feb 17, 2023 - - - -

Logic Workshop
CUNY Graduate Center
Hybrid: Please email Victoria Gitman (vgitman@gmail.com) for meeting id.
Friday February 17, 2:00pm-3:30pm, Room 6417

Russell Miller, CUNY
Computability and the Absolute Galois Group of 

Fix a computable presentation  of the algebraic closure of the rational numbers. The absolute Galois group of the rational numbers, which is precisely the automorphism group of the field , may then be viewed as a collection of paths through a finite-branching tree. Each individual automorphism has a Turing degree. We will use known results in computability to try to build natural countable elementary subgroups of the absolute Galois group. Several intriguing questions in number theory will appear as we measure the extent to which we succeed in doing so.



Next Week in Logic at CUNY:

- - - - Monday, Feb 20, 2023 - - - -



- - - - Tuesday, Feb 21, 2023 - - - -

Models of Peano Arithmetic (MOPA)
Tuesday, February 21, 1:00pm
Virtual (email Victoria Gitman vgitman@gmail.com for meeting id)

Alexei Miasnikov, Stevens Institute of Technology
First-order classification and non-standard models

In this talk I will discuss some recent advances in the first-order classification problem. I will touch on first-order rigidity and quasi finite axiomatization. However, the main point of the presentation is on how, in principle, one can describe all structures which are first-order equivalent to a given one. This leads to non-standard models of algebraic structures (aka non-standard analysis or non-standard arithmetic), which are interesting in their own right.




- - - - Wednesday, Feb 22, 2023 - - - -

The New York City Category Theory Seminar
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York

Special Topic:    TQFT and ComputationThird Lecture.
Speaker:     Joshua Sussan, CUNY.
Date and Time:     Wednesday February 22, 2023, 7:00 - 8:30 PM. IN PERSON TALK.
Title:     Non-semisimple Hermitian TQFTs.

Abstract: Topological quantum field theories coming from semisimple categories build upon interesting structures in representation theory and have important applications in low dimensional topology and physics. The construction of non-semisimple TQFTs is more recent and they shed new light on questions that seem to be inaccessible using their semisimple relatives. In order to have potential applications to physics, these non-semisimple categories and TQFTs should possess Hermitian structures. We will define these structures and give some applications.




- - - - Thursday, Feb 23, 2023 - - - -



- - - - Friday, Feb 24, 2023 - - - -

Logic Workshop
CUNY Graduate Center
Hybrid: Please email Victoria Gitman (vgitman@gmail.com) for meeting id.
Friday February 24, 2:00pm-3:30pm, Room 6417
Johanna Franklin, Hofstra University



- - - - Other Logic News - - - -


- - - - Web Site - - - -

Find us on the web at:  nylogic.github.io
(site designed, built & maintained by Victoria Gitman)

--------  ADMINISTRIVIA  --------

To subscribe/unsubscribe to this list, please email your request to jreitz@nylogic.org.

If you have a logic-related event that you would like included in future mailings, please email jreitz@nylogic.org

Wednesday seminar

Prague Set Theory Seminar
Dear all, The seminar meets on Wednesday February 15th at 11:00 in the Institute of Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building. Program: Chris Lambie-Hanson -- Whitehead's problem, expanded and condensed, Part 2 Whitehead's problem, which asks whether every Whitehead group is a free abelian group, was a prominent open question in group theory in the mid-20th century. In 1974, Shelah proved that the problem is independent of ZFC: if V=L, then every Whitehead group is free, whereas if Martin's Axiom and the negation of CH hold, then there is a non-free Whitehead group. This was a major surprise and was one of the first major problems coming from outside logic and set theory to be proven to be independent. Last week, we sketched a proof of Shelah's independence result. This week, we present some more recent work, focusing on the category of condensed abelian groups, introduced recently by Clausen and Scholze as an enrichment of the category of topological abelian groups with nicer algebraic properties. We will give a new, concrete, combinatorial proof of a result, due to Clausen and Scholze, stating that Whitehead's problem is not independent in the category of condensed abelian groups. We will end by using some of the ideas of this proof to highlight some potential connections between condensed mathematics and the theory of forcing. Best, David

Barcelona Set Theory Seminar

Barcelona Logic Seminar

Dear All, 
Please find attached the announcement of the next Barcelona Set Theory Seminar session.

SPEAKER:  Andreas Lietz
TITLE: Forcing "NS is 
1-Dense" from Large Cardinals
DATE: Wednesday, 15 February 2023
TIME: 16:00 (CET)
PLACE: Room B1 (UB). The Seminar can also be followed online via Zoom:


Best regards,
Joan

P.S.: If you do not wish to receive any more announcements, please send an email to bagaria@ub.edu with the text “Unsubscribe”.



Joan Bagaria 
ICREA Research Professor 
Universitat de Barcelona
Departament de Matemàtiques i Informàtica
Gran Via de les Corts Catalanes 585
08007 Barcelona
Catalonia 

Phone: +34 93 402 1609
joan.bagaria@icrea.cat
bagaria@ub.edu


Nankai Logic Colloquium

Nankai Logic Colloquium

Hello everyone,


This week our weekly Nankai Logic Colloquium is going to be in the afternoon.


Our speaker this week will be Anush Tserunyan from McGill University. This talk is going to take place this Friday, Feb.10, 2023,  from 4 pm to 5 pm (UTC+8, Beijing time). 

Title. A descriptive approach to pointwise ergodic theorems

Abstract. Pointwise ergodic theorems provide a bridge between the global behaviour of the dynamical system and the local combinatorial statistics of the system at a point. These theorems are powerful tools used in ergodic theory, probability, number theory, and other areas of mathematics. I will describe a new general yet elementary approach for proving such theorems, which is inspired by descriptive set theory. This approach has led to new kinds of pointwise ergodic theorems, and I will discuss those obtained in joint work with Jenna Zomback.

___________________________________________________________________________________________________________________________________________________

This is going to be an online event. Follow the link below to join the Zoom meeting. Please use your real name to join the meeting.


Title: The 15th Nankai Logic Colloquium --Anush Tserunyan
Time: 16:00pm, Feb. 10, 2023 (Beijing Time)
Zoom Number:836 2979 3119
Passcode: 476294
Link: https://us02web.zoom.us/j/83629793119?pwd=R1c4OHJReXNMTHE2dFpOOS91bnhQUT09

_____________________________________________________________________


Best wishes,

Ming Xiao




Logic Seminar Wed 8 Feb 2023 17:00 hrs at NUS via Zoom by Will Johnson

NUS Logic Seminar
Invitation to the Logic Seminar at the National Univers