Wednesday seminar
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 Klimit is a countable structure M such that every finitely generated substructure of M is in K. A Klimit U is universal if every Klimit embeds in U. It is wellknown 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 welldefinedness of a certain ordinalvalued 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.
Date: Monday, Sept 18, 4.156.15pm (NY time)
Title: Nonclassicality all the way up
Abstract: Nearly all nonclassical logics that have been studied admit of classical reasoning about them. For example, in the logic K3, A or notA is not a valid schema. However, ‘A or notA’ is K3valid or not K3valid—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 nonclassicality of a logic—one on which almost all familiar nonclassical logics are of the lowest grade of nonclassicality. I’ll then discuss some strategies for generating and theorizing logics of higher grades of nonclassicality, 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/infinitegamesworkshop/
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
    Friday, Sep 22, 2023    
CUNY Graduate Center, Room 5383
Friday, Sept 22, 12:302:00pm
CUNY Graduate Center
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.
    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
    Thursday, Sep 28, 2023    
    Friday, Sep 29, 2023    
CUNY Graduate Center
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
    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 logicrelated 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
This Week in Logic at CUNY
    Monday, Sep 11, 2023    
Rutgers Logic Seminar
Monday, Sept 11th, 3:30pm, Rutgers University, Hill 705
The Tukey order on ultrafilters, the Galvin property, and the Ultrapower Axiom
Logic and Metaphysics Workshop
Date: Monday, Sept 11, 4.156.15pm (NY time)
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 prooftheoretic 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    
    Monday, Sep 18, 2023    
Logic and Metaphysics Workshop
Date: Monday, Sept 18, 4.156.15pm (NY time)
Title: Nonclassicality all the way up
Abstract: Nearly all nonclassical logics that have been studied admit of classical reasoning about them. For example, in the logic K3, A or notA is not a valid schema. However, ‘A or notA’ is K3valid or not K3valid—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 nonclassicality of a logic—one on which almost all familiar nonclassical logics are of the lowest grade of nonclassicality. I’ll then discuss some strategies for generating and theorizing logics of higher grades of nonclassicality, 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    
CUNY Graduate Center, Room 5383
Friday, Sept 22, 12:302:00pm
CUNY Graduate Center
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.
    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 logicrelated event that you would like included in future mailings, please email jreitz@citytech.cuny.edu.
Wednesday seminar
Logic Seminars next week
Logic Seminar Today
This Week in Logic at CUNY
Best,
    Monday, Sep 4, 2023    
COLLEGE CLOSED  Labor Day
    Tuesday, Sep 5, 2023    
    Wednesday, Sep 06, 2023    
    Thursday, Sep 07, 2023    
    Friday, Sep 08, 2023    
CUNY Graduate Center
Hans Schoutens, CUNY
The modeltheory of compact spaces
A more correct title would read: the modeltheory of the category of compact (Hausdorff) spaces. Last year, I gave a talk about the modeltheory 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, 4.156.15pm (NY time)
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 prooftheoretic 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    
    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 logicrelated event that you would like included in future mailings, please email jreitz@citytech.cuny.edu.
(KGRC) talks for the upcoming semester
Wednesday seminar
Logic Seminar 5 Sept 2023 17:00 hrs at NUS by Sun Mengzhou
Logic Seminar 29 Aug 2023 17:00 hrs at NUS by Tran Chieu Minh
Fwd: Aviles
Od: Grzegorz Plebanek <grzegorz.plebanek@math.uni.wroc.pl>
Date: czw., 24 sie 2023 o 20:39
Subject: Aviles
To: Piotr BorodulinNadzieja <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>
Wednesday seminar
Wednesday seminar
Wednesday seminar
Wednesday seminar
Wednesday seminar
RIMS Set Theory Workshop: October 2427, 2023
Wednesday seminar
(KGRC) two talks on Thursday, June 29
Nankai Logic Colloquium
(KGRC) two talks on Tuesday, June 20 and two talks on Thursday, June 22
Wednesday seminar
Conferencias del Seminario Colombo Mexicano de Teoría de Conjuntos 2023I.
(KGRC) TU Wien Mini Workshop and two KGRC talks
CrossAlps Logic Seminar (speaker: André Nies)
All the best,
Vincenzo
Set Theory and Topology Seminar 13.06.2023 Paweł Krupski
Paweł Krupski
(on behalf of the organizers, i.e. Piotr BorodulinNadzieja, 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 C19.
https://settheory.pwr.edu.pl/
http://www.math.uni.wroc.pl/seminarium/topologia
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).
Abstract: A celebrated result of GaoJackson 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 Borelreducible 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
CrossAlps Logic Seminar (speaker: Ulrich Kohlenbach)
All the best,
Vincenzo
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 anticlassification 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 measurepreserving 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 anticlassification 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 nonBorel 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 ForemanRudolphWeisstype construction used for an anticlassification theorem for ergodic automorphisms of the Lebesgue space. We find a continuous map F from the space of all subtrees over nonnegative 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 illfounded if and only if F(T) is topologically conjugate to its inverse. Since the set of illfounded trees with arbitrarily long branches is a wellknown 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 GarcíaRamos, 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)
Piotr Szewczak (UKSW)
(on behalf of the organizers, i.e. Piotr BorodulinNadzieja, 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 nonMenger 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 WeaveUNISONO call in the Weave programme, project: Settheoretic 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 C19.
https://settheory.pwr.edu.pl/
http://www.math.uni.wroc.pl/seminarium/topologia
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
Zbigniew Lipecki (IM PAN)
(on behalf of the organizers, i.e. Piotr BorodulinNadzieja, 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'echetNikodym (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 C19.
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
May 25
4:00 p.m.  5:00 p.m. (Colombia time)
Zoom meeting information.
Meeting ID: 856 1882 0721
Passcode: 123456
https://cuaieedunam.zoom.us/j/85618820721
This Week in Logic at CUNY
    Tuesday, May 23, 2023    
MAMLS Spring Fling at Rutgers University
The MAMLS Spring Fling meeting will take place May 2326 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    
    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 logicrelated event that you would like included in future mailings, please email jreitz@citytech.cuny.edu.
(KGRC) four talks, long and short
Set Theory and Topology Seminar 23.05.2023 Barnabas Farkas
Barnabas Farkas (TU Wien)
(on behalf of the organizers, i.e. Piotr BorodulinNadzieja, Paweł Krupski, Aleksandra Kwiatkowska, Grzegorz Plebanek, Robert Rałowski and myself)
Abstract
About 15 minutes before the seminar we invite you for coffee and a chat to social room A.4.1.A in C19.
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
Mayo 18
4:00 p.m.  5:00 p.m. (hora de Colombia)
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://cuaieedunam.zoom.us/j/85618820721
CrossAlps Logic Seminar (speaker: Jacques Duparc)
All the best,
Vincenzo
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 ZermeloFraenkel set theory without the axiom of choice). In 1906, by virtue of Zermelo's wellordering 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
Logic and Metaphysics Workshop
Date: Monday, May 15, 4.156.15pm (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    
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(yx) P(x) = P(xy) 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    
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 ordertheoretic 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 nonCohen ccc forcings.
    Monday, May 22, 2023    
    Tuesday, May 23, 2023    
MAMLS Spring Fling at Rutgers University
The MAMLS Spring Fling meeting will take place May 2326 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    
    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 logicrelated event that you would like included in future mailings, please email jreitz@citytech.cuny.edu.
Applications of Set Theory, Lodz, Poland, September 48 2023
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 modeltheoretic 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.
__________________________________________________________________________________________________
Best wishes,
Ming Xiao
Charla de Jose Moncayo en el 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)
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.
Zoom meeting information.
Meeting ID: 856 1882 0721
Passcode: 123456
https://cuaieedunam.zoom.us/j/85618820721
This Week in Logic at CUNY
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    
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, 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 AbdulQuader (Pathologically definable subsets of models of CT), however we will make sure to make it selfcontained.
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 DCset 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 DCset 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 IDCset 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 AbdulQuader 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
10:0011:30: 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 wellmotivated in the context of connexive logic. Both nonstandard quantifiers have been introduced previously, but in the context of connexive logic they have a natural semantic and prooftheoretic place, and plausible natural language readings. The result are logics which are negation inconsistent but nontrivial.
Note: This is joint work with Zach Weber (Otago).
12:302:00: Daniel Skurt (Bochum)
Title: RNmatrices for modal logics
Abstract: In this talk we will introduce a semantics for modal logics, based on socalled 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 nonnormal systems of modal logics. Each of these semantics have sound and complete Hilbertstyle calculi. The advantage of RNmatrices is that they provide a unifying framework for modal logics with or without firstorder Kripkeframe conditions.
Note: This is joint work with Marcelo Coniglio (Campinas) and Pawel Pawlowski (Ghent).
2:304:00: Mark Colyvan (Sydney/LMU)
Title: Explanatory and nonexplanatory proofs in mathematics
Abstract: In this paper I look at the contrast between explanatory and nonexplanatory 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    
CUNY Graduate Center
Brian Wynne, CUNY
Recent developments in the model theory of Abelian latticeordered groups
An Abelian latticeordered 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 realvalued functions on the topological space with pointwise operations and ordering. Let be the class of groups, viewed as structures for the firstorder 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 .
    Monday, May 15, 2023    
Logic and Metaphysics Workshop
Date: Monday, May 15, 4.156.15pm (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    
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(yx) P(x) = P(xy) 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    
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 ordertheoretic 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 nonCohen ccc forcings.
    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 logicrelated event that you would like included in future mailings, please email jreitz@citytech.cuny.edu.
(KGRC) Set Theory Seminar talk on TUESDAY, May 9
Wednesday seminar
Logic Seminar 10 May 2023 17:00 hrs at NUS by Jan Baars
CrossAlps Logic Seminar (speaker: Dima Sinapova)
All the best,
Vincenzo
Charla de Joel Aguilar en el 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 nonumerable, 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://cuaieedunam.zoom.us/
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 wellknown 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 2element 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.
__________________________________________________________________________________________________
Best wishes,
Ming Xiao
Wednesday seminar
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 wellknown 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 2element 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.
__________________________________________________________________________________________________
Best wishes,
Ming Xiao
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 wellknown 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 2element 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.
__________________________________________________________________________________________________
Best wishes,
Ming Xiao
This Week in Logic at CUNY
Logic and Metaphysics Workshop
Date: Monday, May 1, 4.156.15pm (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/
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    
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 nontrivial 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    
CUNY Graduate Center
Virtual: Please email Victoria Gitman (vgitman@gmail.com) for meeting id.
Realizing Frege's Basic Law V, provably in ZFC
The standard settheoretic 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 firstorder 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.
CUNY Graduate Center
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.
    Monday, May 8, 2023    
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    
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, 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 AbdulQuader (Pathologically definable subsets of models of CT), however we will make sure to make it selfcontained.
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 DCset 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 DCset 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 IDCset 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 AbdulQuader 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
10:0011:30: 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 wellmotivated in the context of connexive logic. Both nonstandard quantifiers have been introduced previously, but in the context of connexive logic they have a natural semantic and prooftheoretic place, and plausible natural language readings. The result are logics which are negation inconsistent but nontrivial.
Note: This is joint work with Zach Weber (Otago).
12:302:00: Daniel Skurt (Bochum)
Title: RNmatrices for modal logics
Abstract: In this talk we will introduce a semantics for modal logics, based on socalled 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 nonnormal systems of modal logics. Each of these semantics have sound and complete Hilbertstyle calculi. The advantage of RNmatrices is that they provide a unifying framework for modal logics with or without firstorder Kripkeframe conditions.
Note: This is joint work with Marcelo Coniglio (Campinas) and Pawel Pawlowski (Ghent).
2:304:00: Mark Colyvan (Sydney/LMU)
Title: Explanatory and nonexplanatory proofs in mathematics
Abstract: In this paper I look at the contrast between explanatory and nonexplanatory 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    
CUNY Graduate Center
Brian Wynne, CUNY
Recent developments in the model theory of Abelian latticeordered groups
An Abelian latticeordered 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 realvalued functions on the topological space with pointwise operations and ordering. Let be the class of groups, viewed as structures for the firstorder 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 .
CONFERENCE ANNOUNCEMENT
    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 logicrelated event that you would like included in future mailings, please email jreitz@citytech.cuny.edu.
(KGRC) two talks on Thursday, May 4
Charla de Diana Montoya en el 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)
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.
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 BeckerKechris 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 BeckerKechris 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 nonHausdorff spaces, Borel firstorder $G$structures, and groupoid actions.
__________________________________________________________________________________________________
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
Date: Monday, April 24, 4.156.15pm (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/
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)
Pathologies in Satisfaction Classes
This is the second part of the talk given by Athar AbdulQuader (Pathologically definable subsets of models of CT), however we will make sure to make it selfcontained.
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 DCset 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 DCset 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 IDCset 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 AbdulQuader presented in this paper from arxiv: arXiv:2303.18069v1 [math.LO] 31 Mar 2023.
    Wednesday, Apr 26, 2023    
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: Programclosed 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 wellordered object P with a *program closure*: a family of Xnatural 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 runpreserving morphisms. The result counters Kleene's interpretation of the ChurchTuring 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    
CUNY Graduate Center
Virtual: Please email Victoria Gitman (vgitman@gmail.com) for meeting id.
    Monday, May 1, 2023    
    Tuesday, May 2, 2023    
    Wednesday, May 3, 2023    
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 nontrivial 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    
CUNY Graduate Center
Virtual: Please email Victoria Gitman (vgitman@gmail.com) for meeting id.
CUNY Graduate Center
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.
CONFERENCE ANNOUNCEMENT
    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 logicrelated 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
Wednesday seminar  joint seminar of the MLTCS department
Charla de Andrés Uribe en el 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)
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 FAMligadura, 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.
CrossAlps Logic Seminar (speaker: Márton Elekes)
All the best,
Vincenzo
Nankai Logic Colloquium
Hello everyone,
This week our weekly Nankai Logic Colloquium is going to be in the afternoon.
_____________________________________________________________________
Best wishes,
Ming Xiao
This Week in Logic at CUNY
Date: Monday, April 17, 4.156.15pm (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/
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 Adamsstyle conditional to various probability calculi.
    Tuesday, Apr 18, 2023    
Tuesday, April 18, 1:00pm
Virtual (email Victoria Gitman vgitman@gmail.com for meeting id)
Katarzyna W. Kowalik, University of Warsaw
The chainantichain principle and proof size
The chainantichain principle is a wellknown 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 nonelementary 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    
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 GabrielUlmer 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_ispaces (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 T1separation 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    
CUNY Graduate Center
Virtual: Please email Victoria Gitman (vgitman@gmail.com) for meeting id.
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.
CUNY Graduate Center
How bad could it be? The semilattice of definable sets in continuous logic
Continuous firstorder logic is a generalization of discrete firstorder 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 firstorder theory. We will then discuss a partial extension of this to certain infinite semilattices.
    Monday, Apr 24, 2023    
Date: Monday, April 24, 4.156.15pm (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/
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)
    Wednesday, Apr 26, 2023    
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: Programclosed 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 wellordered object P with a *program closure*: a family of Xnatural 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 runpreserving morphisms. The result counters Kleene's interpretation of the ChurchTuring 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    
CUNY Graduate Center
Virtual: Please email Victoria Gitman (vgitman@gmail.com) for meeting id.
    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 logicrelated event that you would like included in future mailings, please email jreitz@citytech.cuny.edu.
Wednesday seminar
(KGRC) two talks on Thursday, April 20
Fwd: Announcement  PhDs in Logic
Dear colleagues,
We would like to announce the XIV edition of the conference PhDs in Logic 2023 that will take place in Granada, Spain, 46 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/ayudasajovenesinvestigadoresparalaasistenciaacongresosinternacionales2/

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 TorresJose SantiagoDaira PintoJuan M Santiago
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
Abril 13
4:00 p.m.  5:00 p.m. (hora de Colombia)
Universidad Nacional Autónoma de México
Resumen. Los espacios de JohnsonLindentrauss 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 psiespacio.
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.
Logic Seminar 12 April 2023 17:00 hrs at NUS by Daniel Hoffmann via Zoom
This Week in Logic at CUNY
Rutgers Logic Seminar  TODAY'S SEMINAR CANCELLED
    Tuesday, Apr 11, 2023    
*** April 513, 2023 Spring Recess CUNY Graduate Center ***
    Wednesday, Apr 12, 2023    
*** April 513, 2023 Spring Recess CUNY Graduate Center ***
    Thursday, Apr 13, 2023    
    Friday, Apr 14, 2023    
CUNY Graduate Center
Virtual: Please email Victoria Gitman (vgitman@gmail.com) for meeting id.
    Monday, Apr 17, 2023    
Date: Monday, April 17, 4.156.15pm (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/
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 Adamsstyle conditional to various probability calculi.
    Tuesday, Apr 18, 2023    
Tuesday, April 18, 1:00pm
Virtual (email Victoria Gitman vgitman@gmail.com for meeting id)
    Wednesday, Apr 19, 2023    
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 GabrielUlmer 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_ispaces (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 T1separation 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    
CUNY Graduate Center
Virtual: Please email Victoria Gitman (vgitman@gmail.com) for meeting id.
CUNY Graduate Center
    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 logicrelated event that you would like included in future mailings, please email jreitz@citytech.cuny.edu.
Nankai Logic Colloquium
Hello everyone,
This week our weekly Nankai Logic Colloquium is going to be in the morning.
_____________________________________________________________________
Best wishes,
Ming Xiao
Logic Seminar 12 April 2023 17:00 hrs at NUS by Daniel Hoffmann via Zoom
Wednesday seminar
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).
___________________________________________________________________________________________________________________________________________________
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
Logic and Metaphysics Workshop
Date: Monday, April 3, 4.156.15pm (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: Caretheoretic semantics: Problems and nondeterministic solutions
Abstract: In this talk I will present the details of a project of caretheoretic 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 topictheoretic and truththeoretic 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 contenttheoretic 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 caretheoretic setting.
    Tuesday, Apr 4, 2023    
    Wednesday, Apr 5, 2023    
*** April 513, 2023 Spring Recess CUNY Graduate Center ***
    Thursday, Apr 6, 2023    
    Friday, Apr 7, 2023    
CUNY Graduate Center
Virtual: Please email Victoria Gitman (vgitman@gmail.com) for meeting id.
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 ordertheoretic 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 nonCohen ccc forcings.
    Monday, Apr 10, 2023    
Rutgers Logic Seminar
Monday, April 10, 2pm, Rutgers University, Hill 005
Jensen's forcing at an inaccessible
    Tuesday, Apr 11, 2023    
    Wednesday, Apr 12, 2023    
    Thursday, Apr 13, 2023    
    Friday, Apr 14, 2023    
    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 logicrelated event that you would like included in future mailings, please email Jonas.Reitz12@citytech.cuny.edu.
Wednesday seminar
Logic Seminar 5 April 2023 17:00 hrs at NUS by Frank Stephan
Core Model Seminar next Tuesday
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
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 tailend 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
nonreflecting stationary set. One can prove, using a fairly standard
argument, that if the iteration described above uses complements of
nonreflecting 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 nonreflecting 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 ForemanMagidorZeman on games with filters.
Charla de Daniel Calderón en el 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)
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.
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).
___________________________________________________________________________________________________________________________________________________
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
CrossAlps Logic Seminar (speaker: Ludovic Patey)
All the best,
Vincenzo
Logic Seminar Wednesday 29 March 2023 17:00 hrs at NUS by Xie Ruofei
This Week in Logic at CUNY
    Monday, Mar 27, 2023    
Date: Monday, March 27, 4.156.15pm (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: Firstorder logics over fixed domain
Abstract: What we call firstorder 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 prooftheoretically and argue that they constitute exploration of a clearly circumscribed conception of domaindependent 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    
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 BellantoniCook(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 multitape Turing machine each into 2 stacks of digits 1 & 2. These are (modulo allowing an odd numberof stacks) the multistack 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, 2comprehensions, 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 multistack 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 BellantoniCook 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    
CUNY Graduate Center
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.
CUNY Graduate Center
Corey Switzer, University of Vienna
GaloisTukey 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 ZFCinequalities 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 GaloisTukey reduction: the (ZFCprovable) 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 nonprovable 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 nonZFC provable implications thus these cardinals are all as different as possible.
    Monday, Apr 3, 2023    
Logic and Metaphysics Workshop
Date: Monday, April 3, 4.156.15pm (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: Caretheoretic semantics: Problems and nondeterministic solutions
Abstract: In this talk I will present the details of a project of caretheoretic 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 topictheoretic and truththeoretic 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 contenttheoretic 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 caretheoretic setting.
    Tuesday, Apr 4, 2023    
    Wednesday, Apr 5, 2023    
*** April 513, 2023 Spring Recess CUNY Graduate Center ***
    Thursday, Apr 6, 2023    
    Friday, Apr 7, 2023    
CUNY Graduate Center
Virtual: Please email Victoria Gitman (vgitman@gmail.com) for meeting id.
    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 logicrelated event that you would like included in future mailings, please email Jonas.Reitz12@citytech.cuny.edu.
Wednesday seminar
(KGRC) guests, video recordings and notes, and four talks
Charla de Slawomir Solecki en el 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)
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 nonuniform. 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 GlasnerWeiss question in the negative: for a generic measure preserving transformation $T$, the closed group generated by $T$ is not topologically isomorphic to $L^0$.
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).
If $d$ is a compatible leftinvariant 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 SchneiderThom and C\'uthDoucha.
___________________________________________________________________________________________________________________________________________________
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
This Week in Logic at CUNY
Absolute Undefinability
Date: Monday, March 20th, 4.156.15 (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 senderreceiver model
Abstract: The senderreceiver 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 senderreceiver 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    
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 nonconservativity 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_1like 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
Parameterfree comprehension in secondorder arithmetic
Secondorder arithmetic has two types of objects: numbers and sets of numbers, which we think of as the reals. The secondorder 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 secondorder arithmetic axiomatizations is the theory consisting of the axioms (for numbers), the set induction axiom, and comprehension for all secondorder 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 parameterfree 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 subposet of Sacks forcing constructed by Jensen to show that it is consistent to have a nonconstructible definable singleton real (every definable set of reals is constructible by Shoenfield's Absoluteness).
    Monday, Mar 27, 2023    
Date: Monday, March 27, 4.156.15pm (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: Firstorder logics over fixed domain
Abstract: What we call firstorder 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 prooftheoretically and argue that they constitute exploration of a clearly circumscribed conception of domaindependent 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    
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 BellantoniCook(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 multitape Turing machine each into 2 stacks of digits 1 & 2. These are (modulo allowing an odd numberof stacks) the multistack 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, 2comprehensions, 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 multistack 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 BellantoniCook 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    
CUNY Graduate Center
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.
CUNY Graduate Center
    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 logicrelated event that you would like included in future mailings, please email jreitz@nylogic.org. v
Wednesday seminar
(KGRC) Set Theory Seminar talk and Geometry and Analysis on Groups Seminar talk
Logic Seminar today in person in S17#0511
Nankai Logic Colloquium
Hello everyone,
This week our weekly Nankai Logic Colloquium is going to be in the morning.
___________________________________________________________________________________________________________________________________________________
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
Marzo 16
4:00 p.m.  5:00 p.m. (Hora de Colombia)
Universidad de York
Abstract. Diremos que una familia MAD es pseudocompacta, si el hiperespacio de su 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 y la de su hiperespacio .
Este es un trabajo conjunto con Vinicius de Oliveira Rodrigues.
CrossAlps Logic Seminar (speaker: Victor Selivanov)
All the best,
Vincenzo
CosmoCaixa Barcelona: Joel Hamkins: pensament estratègic en jocs infinits
neal
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
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
This Week in Logic at CUNY
    Monday, Mar 13, 2023    
Logic and Metaphysics Workshop
Date: Monday, March 13, 4.156.15pm (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 nonconservativity 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_1like end extension M' such that M' carries a full satisfaction class.
    Wednesday, Mar 15, 2023    
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York
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    
CUNY Graduate Center
Virtual: Please email Victoria Gitman (vgitman@gmail.com) for meeting id.
Jonathan Osinski, University of Hamburg
ModelTheoretic 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.
CUNY Graduate Center
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.
    Monday, Mar 20, 2023    
Absolute Undefinability
Date: Monday, March 20, 4.156.15pm (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: Firstorder logics over fixed domain
Abstract: What we call firstorder 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 prooftheoretically and argue that they constitute exploration of a clearly circumscribed conception of domaindependent 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
    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 logicrelated event that you would like included in future mailings, please email jreitz@nylogic.org.
(KGRC) talks on Tuesday, March 14 and Thursday, March 16
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 2ndorder 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 parameterfree subschema. Kreisel (A survey of proof theory, JSL 1968) was one of those who paid attention to the comparison of some schemata in secondorder PA and their parameterfree 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 secondorder arithmetic.
_____________________________________________________________________
Best wishes,
Ming Xiao
UPDATE  This Week in Logic at CUNY
Logic and Metaphysics Workshop
Date: Monday, March 6, 4.156.15pm (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/
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 contextsensitivity of de re modal predication: (1) and (2) make implicit, contextsensitive reference to different counterpart relations. Once we recognize this, Lewisians argue, it becomes clear how our intuitive truthconditional 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 [13], 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), 103109.
[2] A. Boudaoud and D. Bellaouar, Representation of integers: A nonclassical point of view, J. Log. Anal. 12:4 (2020) 131.
[3] K. Hrbacek, On Factoring of unlimited integers, J. Log. Anal. 12:5 (2020) 16.
    Wednesday, Mar 8, 2023    
    Thursday, Mar 9, 2023    
    Friday, Mar 10, 2023    
CUNY Graduate Center
CUNY Graduate Center
Virtual: Please email Victoria Gitman (vgitman@gmail.com) for meeting id.
    Monday, Mar 13, 2023    
Logic and Metaphysics Workshop
Date: Monday, March 13, 4.156.15pm (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)
    Wednesday, Mar 15, 2023    
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York
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    
CUNY Graduate Center
Virtual: Please email Victoria Gitman (vgitman@gmail.com) for meeting id.
CUNY Graduate Center
Modality TBA
    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 logicrelated 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
March 9
4:00 p.m.  5:00 p.m. (Colombia time)
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 is the leader in modern enterprise video communications, with an easy, reliable cloud platform for video and audio conferencing, chat, and webinars across mobile, desktop, and room systems. Zoom Rooms is the original softwarebased conference room solution
used around the world in board, conference, huddle, and training rooms, as well as executive offices and classrooms. Founded in 2011, Zoom helps businesses and organizations bring their teams together in a frictionless environment to get more done. Zoom is
a publicly traded company headquartered in San Jose, CA.
cuaieedunam.zoom.us

This Week in Logic at CUNY
Logic and Metaphysics Workshop
Date: Monday, March 6, 4.156.15pm (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/
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 contextsensitivity of de re modal predication: (1) and (2) make implicit, contextsensitive reference to different counterpart relations. Once we recognize this, Lewisians argue, it becomes clear how our intuitive truthconditional 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 [13], 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), 103109.
[2] A. Boudaoud and D. Bellaouar, Representation of integers: A nonclassical point of view, J. Log. Anal. 12:4 (2020) 131.
[3] K. Hrbacek, On Factoring of unlimited integers, J. Log. Anal. 12:5 (2020) 16.
    Wednesday, Mar 8, 2023    
    Thursday, Mar 9, 2023    
    Friday, Mar 10, 2023    
CUNY Graduate Center
Modality TBA
CUNY Graduate Center
Virtual: Please email Victoria Gitman (vgitman@gmail.com) for meeting id.
    Monday, Mar 13, 2023    
Logic and Metaphysics Workshop
Date: Monday, March 13, 4.156.15pm (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)
    Wednesday, Mar 15, 2023    
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York
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    
CUNY Graduate Center
Virtual: Please email Victoria Gitman (vgitman@gmail.com) for meeting id.
CUNY Graduate Center
Modality TBA
    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 logicrelated event that you would like included in future mailings, please email jreitz@nylogic.org.
Barcelona Set Theory Seminar
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
(KGRC) two talks at U Wien and TU Wien
CosmoCaixa Barcelona: Joel Hamkins: pensament estratègic en jocs infinits
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
Today's Logic Seminar is via Zoom
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).
___________________________________________________________________________________________________________________________________________________
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
CrossAlps Logic Seminar (speaker: Dugald MacPherson)
All the best,
Vincenzo
(KGRC) Logic Colloquium talk on Thursday, March 2
Wednesday seminar
This Week in Logic at CUNY
Ramsey's Theorem in the countable and weak randomness
Date: Monday, February 27, 4.156.15pm (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/
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    
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    
    Monday, Mar 6, 2023    
Logic and Metaphysics Workshop
Date: Monday, March 6, 4.156.15pm (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/
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 contextsensitivity of de re modal predication: (1) and (2) make implicit, contextsensitive reference to different counterpart relations. Once we recognize this, Lewisians argue, it becomes clear how our intuitive truthconditional 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 [13], 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), 103109.
[2] A. Boudaoud and D. Bellaouar, Representation of integers: A nonclassical point of view, J. Log. Anal. 12:4 (2020) 131.
[3] K. Hrbacek, On Factoring of unlimited integers, J. Log. Anal. 12:5 (2020) 16.
    Wednesday, Mar 8, 2023    
    Thursday, Mar 9, 2023    
    Friday, Mar 10, 2023    
CUNY Graduate Center
Modality TBA
CUNY Graduate Center
Virtual: Please email Victoria Gitman (vgitman@gmail.com) for meeting id.
    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 logicrelated event that you would like included in future mailings, please email jreitz@nylogic.org.
Barcelona Set Theory Seminar
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 1620, 2023
CMU Math Logic Seminar next Tuesday
Mathematical Logic Seminar: 3:304:30 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 oneended 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
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 transformationsAbstract: 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 nonuniform. 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 GlasnerWeiss 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
    Monday, Feb 13, 2023    
Forcing more choice over the Chang model
    Tuesday, Feb 14, 2023    
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 2ndorder 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 parameterfree subschema.
Kreisel (A survey of proof theory, JSL 1968) was one of those who paid attention to the comparison of some schemata in secondorder PA and their parameterfree 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 secondorder arithmetic.
    Wednesday, Feb 15, 2023    
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York
Special Topic: TQFT and Computation, Second 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 Booleanvalued onedimensional 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 onedimensional TQFT.
    Thursday, Feb 16, 2023    
    Friday, Feb 17, 2023    
CUNY Graduate Center
Hybrid: Please email Victoria Gitman (vgitman@gmail.com) for meeting id.
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 finitebranching 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.
    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
Firstorder classification and nonstandard models
In this talk I will discuss some recent advances in the firstorder classification problem. I will touch on firstorder rigidity and quasi finite axiomatization. However, the main point of the presentation is on how, in principle, one can describe all structures which are firstorder equivalent to a given one. This leads to nonstandard models of algebraic structures (aka nonstandard analysis or nonstandard arithmetic), which are interesting in their own right.
    Wednesday, Feb 22, 2023    
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York
Special Topic: TQFT and Computation, Third Lecture.
Speaker: Joshua Sussan, CUNY.
Date and Time: Wednesday February 22, 2023, 7:00  8:30 PM. IN PERSON TALK.
Title: Nonsemisimple 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 nonsemisimple 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 nonsemisimple categories and TQFTs should possess Hermitian structures. We will define these structures and give some applications.
    Thursday, Feb 23, 2023    
    Friday, Feb 24, 2023    
CUNY Graduate Center
Hybrid: Please email Victoria Gitman (vgitman@gmail.com) for meeting id.
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 zeroone 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 MengChe 'Turbo' Ho and Julia Knight.
    Monday, Feb 27, 2023    
Logic and Metaphysics Workshop
Date: Monday, February 27, 4.156.15pm (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/
    Tuesday, Feb 28, 2023    
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    
    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 logicrelated event that you would like included in future mailings, please email jreitz@nylogic.org.
Wednesday seminar
Barcelona Set Theory Seminar
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
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
    Monday, Feb 13, 2023    
Forcing more choice over the Chang model
    Tuesday, Feb 14, 2023    
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 2ndorder 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 parameterfree subschema.
Kreisel (A survey of proof theory, JSL 1968) was one of those who paid attention to the comparison of some schemata in secondorder PA and their parameterfree 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 secondorder arithmetic.
    Wednesday, Feb 15, 2023    
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York
Special Topic: TQFT and Computation, Second 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 Booleanvalued onedimensional 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 onedimensional TQFT.
    Thursday, Feb 16, 2023    
    Friday, Feb 17, 2023    
CUNY Graduate Center
Hybrid: Please email Victoria Gitman (vgitman@gmail.com) for meeting id.
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 finitebranching 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.
    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
Firstorder classification and nonstandard models
In this talk I will discuss some recent advances in the firstorder classification problem. I will touch on firstorder rigidity and quasi finite axiomatization. However, the main point of the presentation is on how, in principle, one can describe all structures which are firstorder equivalent to a given one. This leads to nonstandard models of algebraic structures (aka nonstandard analysis or nonstandard arithmetic), which are interesting in their own right.
    Wednesday, Feb 22, 2023    
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York
Special Topic: TQFT and Computation, Third Lecture.
Speaker: Joshua Sussan, CUNY.
Date and Time: Wednesday February 22, 2023, 7:00  8:30 PM. IN PERSON TALK.
Title: Nonsemisimple 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 nonsemisimple 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 nonsemisimple categories and TQFTs should possess Hermitian structures. We will define these structures and give some applications.
    Thursday, Feb 23, 2023    
    Friday, Feb 24, 2023    
CUNY Graduate Center
Hybrid: Please email Victoria Gitman (vgitman@gmail.com) for meeting id.
    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 logicrelated event that you would like included in future mailings, please email jreitz@nylogic.org.
Wednesday seminar
Barcelona Set Theory Seminar
DATE: Wednesday, 15 February 2023
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
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).
___________________________________________________________________________________________________________________________________________________
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.
_____________________________________________________________________
Best wishes,
Ming Xiao