Set Theory Talks

Global set theory seminar and conference announcements

Set Theory and Topology Seminar 5.12.2023 Daria Perkowska

Wrocław Set Theory Seminar
I am happy to announce that at the seminar in Set Theory and Topology on Tuesday 5.12.2023 at 17:15 in room 601 (Mathematical Institute, University of Wrocław) the lecture:
"Non-meager filters"

will be presented by

Daria Perkowska


Abstract.

In the talk I will consider filters on \omega in the measurability (and complexity) context.  Also, one can distinguish some natural subclasses of non-meager filters. We say that a filter F is ccc if P(\omega) /F is ccc. Similarly, we say that a filter supports a measure if there is a probability measure \mu on \omega such that F = {A: \mu(A)=1}. I will show that every ultrafilter supports a measure, every measure supporting filter is ccc and every ccc filter is non-meager. So, one can think about these notions as forming some hierarchy of complexity of filters. This hierarchy is strict. Next I will show that for every ultrafilter from the forcing extension (by \mathbb{A}), there is a ground model filter F such that the ultrafilter extends F and there is an injective Boolean homomorphism \varphi: P(\omega) /F \to \mathbb{A}.


Feel free to spread this information among Your colleagues.

I'm looking forward to seeing You
Szymon Żeberski

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

About 15 minutes before the seminar we invite you for coffee and a chat to social room.


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

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

36th Nankai Logic Colloquium

Nankai Logic Colloquium

Hello everyone,

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

Our speaker this week will be Victor Hugo Yanez from Nanjing Normal University. This talk is going to take place this Friday, Dec 01, from 4pm to 5pm(UTC+8, Beijing time). 


Title: An introduction to the Markov and Zariski topologies of a group

Abstract: Let $G$ be a group. A subset of $X$ is said to be \emph{elementary algebraic}, if it is the solution set on $G$ of a given equation of the form $g_1 x^{\varepsilon_1} g_2 x^{\varepsilon_2} \cdots g_n x^{\varepsilon_n} = 1$ for some $g_1, \dots, g_n \in G$ and integers $\varepsilon_1, \dots, \varepsilon_n \in \Z$. $X$ is \emph{algebraic} whenever it is an intersection of a finite union of elementary algebraic subsets of $G$. The algebraic subsets of a group $G$ form a basis of closed sets for a unique topology on $G$ known as the Zariski topology of $G$. Meanwhile, the family of all subsets of $G$ which are closed in every Hausdorff group topology of $G$ form a family of closed subsets for another unique topology on $G$ known as the \emph{Markov topology} of $G$. The Markov topology on a group is always finer than its Zariski topology. 

An old 1945 problem of Markov asks whether the Markov and Zariski topologies of a group must always coincide. The goal of this talk is to give a humble introduction to the theory of the Markov and Zariski topologies; from the overall motivation and impact of the classic results of Markov, to more recent advances further enriching the solution of Markov's problem.

_____________________________________________________________________________________________________

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

Title :The 36th Nankai Logic Colloquium --Victor Hugo Yañez
Time :16:00pm, Dec. 1, 2023(Beijing Time)
Zoom Number : 671 670 2069
Passcode : 773654
Link :https://us05web.zoom.us/j/6716702069?pwd=mhCy9U60VrE8F6YSCOxOlGxIDPFTgx.1&omn=89006488717

_____________________________________________________________________


Best wishes,

Ming Xiao






(KGRC) two seminar talks Thursday, November 30

Kurt Godel Research Center
(The announcements sent a few minutes ago stated the wrong title for Professor Andretta's talk. Below are the corrected announcements. Apologies for any confusion caused!) * * * The KGRC welcomes as guests: David Schrittesser (host: Vera Fischer) visits the KGRC until January 8, 2024. * * * Set Theory Seminar Kurt Gödel Research Center Thursday, November 30 "Forcing techniques for Cichoń's Maximum" Diego Alejandro Mejía (Shizuoka U, JP) Mini-course (30.11.2023-25.01.2024, 6 lectures) - 1st lecture: Cichoń's diagram describes the connections between combinatorial notions related to measure, category, and compactness of sets of irrational numbers. In the second part of the 2010's decade, Goldstern, Kellner and Shelah constructed a forcing model of Cichoń's Maximum (meaning that all non-dependent cardinal characteristics are pairwise different) by using large cardinals. Some years later, we eliminated this large cardinal assumption. In this mini-course, we explore the forcing techniques to construct the Cichoń's Maximum model and much more. Concretely, we discuss the following components: 1. Tukey connections and cardinal characteristics of the continuum 2. Review of FS (finite support) iterations and basic methods to modify cardinal characteristics. 3. Preservation theory for cardinal characteristics. 4. FS iterations with measures and ultrafilters on the natural numbers. 5. Boolean Ultrapowers. 6. Forcing Intersected with submodels. Time and Place Talk at 11:30am in hybrid mode: on-site as well as via Zoom Universität Wien Institut für Mathematik Kolingasse 14-16 1090 Wien 1st floor Seminar room 10 Zoom: If you have not received the Zoom data by the day before the talk, please contact richard.springer@univie.ac.at. Please direct any other questions about this talk to vera.fischer@univie.ac.at. * * * Logic Colloquium Kurt Gödel Research Center Thursday, November 30 "Sierpiński's theorem: geometric aspects and definability issues" Alessandro Andretta (U of Turin, IT) There are numerous statements in various areas of mathematics (algebra, analysis, geometry, ...) that are equivalent to the continuum hypothesis (CH). The earliest instance of this phenomenon is Sierpiński's theorem from 1919: CH is equivalent to the existence of two sets covering the plane such that every horizontal line has countable intersection with the first set and every vertical line has countable intersection with the second. Sierpiński's theorem is the blueprint for most other geometric facts that are equivalent to CH. I will survey some of these theorems proved in the last hundred years, and present some new results in this area. Time and Place Talk at 3:00pm in hybrid mode: on-site as well as via Zoom Universität Wien Institut für Mathematik Oskar-Morgenstern-Platz 1 1090 Wien 2nd floor room HS 11 Zoom: If you have not received the Zoom data by the day before the talk, please contact richard.springer@univie.ac.at. Please direct any other questions about this talk to vera.fischer@univie.ac.at.

Cross-Alps Logic Seminar (speaker: Zoltán Vidnyánszky)

Cross-Alps Logic Seminar
On Friday 01.12.2023 at 16.00
Zoltán Vidnyánszky (Eötvös Loránd University)
will give a talk on 
Homomorphisms in the choiceless world

Please refer to the usual webpage of our LogicGroup for more details and the abstract of the talk.

The seminar will be held remotely through Webex. Please write to vincenzo.dimonte [at] uniud [dot] it for the link to the event.

The Cross-Alps Logic Seminar is co-organized by the logic groups of Genoa, Lausanne, Turin and Udine as part of our collaboration in the project PRIN 2022 'Models, Sets and Classifications'.

All the best,
Vincenzo

This Week in Logic at CUNY

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

- - - - Monday, Nov 27, 2023 - - - -

Logic and Metaphysics Workshop
Date: Monday, Nov 27, 4.15-6.15pm (NY time)
Room: Graduate Center Room 4419
Mircea Dumitru (Bucharest).
Title: Truth with and without satisfaction

Abstract: The talk addresses a quite natural situation in mathematics. When one needs to define a concept and it is not possible to do a direct recursion on the concept itself, what one does is the next best thing which is to perform recursion on a related concept of which the original given concept can be shown to be a special case. Tarski, in his celebrated paper on “The Concept of Truth in Formalized Languages”, cannot give a definition of truth performing direct recursion on the concept of truth itself. Consequently, he settles on a definition in terms of satisfaction. Following Kit Fine and Timothy McCarthy, “Truth without Satisfaction”, I raise the issue of whether such an indirect procedure of giving a definition of truth is necessary or maybe an alternative definition of truth can be given without going through the related concept of satisfaction. My talk will investigate both certain technical and philosophical aspects of the two sets of formal constraints to defining truth with and without satisfaction.





- - - - Tuesday, Nov 28, 2023 - - - -



- - - - Wednesday, Nov 29, 2023 - - - -

The New York City Category Theory Seminar
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York
URL:  http://www.sci.brooklyn.cuny.edu/~noson/Seminar/index.html
Speaker:     Charlotte Aten, University of Denver.
Date and Time:     Wednesday November 29, 2023, 7:00 - 8:30 PM. ZOOM TALK.
Title:     A categorical semantics for neural networks.

Abstract: In recent work on discrete neural networks, I considered such networks whose activation functions are polymorphisms of finite, discrete relational structures. The general framework I provided was not entirely categorical in nature but did provide a stepping stone to a categorical treatment of neural nets which are definitionally incapable of overfitting. In this talk I will outline how to view neural nets as categories of functors from certain multicategories to a target multicategory. Moreover, I will show that the results of my PhD thesis allow one to systematically define polymorphic learning algorithms for such neural nets in a manner applicable to any reasonable (read: functorial) finite data structure.




- - - - Thursday, Nov 30, 2023 - - - -



- - - - Friday, Dec 1, 2023 - - - -

Model Theory Seminar
Friday, Dec 1, 12:30-2:00pm NY time, Room 5383

Rehana Patel Wesleyan University



Logic Workshop
CUNY Graduate Center
Friday Dec 1, 2:00pm-3:30pm, Room 6417

James Walsh, New York University
Is the consistency operator canonical?

It is a well-known empirical phenomenon that natural axiomatic theories are well-ordered by consistency strength. The restriction to natural theories is necessary; using ad-hoc techniques (such as self-reference and Rosser orderings) one can exhibit non-linearity and ill-foundedness in the consistency strength hierarchy. What explains the contrast between natural theories and axiomatic theories in general?

Our approach to this problem is inspired by work on an analogous problem in recursion theory. The natural Turing degrees  are well-ordered by Turing reducibility, yet the Turing degrees in general are neither linearly ordered nor well-founded, as ad-hoc techniques (such as the priority method) bear out. Martin's Conjecture, which is still unresolved, is a proposed explanation for this phenomenon. In particular, Martin’s Conjecture specifies a way in which the Turing jump is canonical.

After discussing Martin’s Conjecture, we will formulate analogous proof-theoretic hypotheses according to which the consistency operator is canonical. We will then discuss results - both positive and negative - within this framework. Some of these results were obtained jointly with Antonio Montalbán.





Next Week in Logic at CUNY:

- - - - Monday, Dec 4, 2023 - - - -

Rutgers Logic Seminar
Monday, Dec 4, 3:30pm, Rutgers University, Hill 705
Joel David Hamkins, Notre Dame
The computable model theory of forcing



Logic and Metaphysics Workshop
Date: Monday, Dec 4, 4.15-6.15pm (NY time)
Room: Graduate Center Room 4419

James Walsh (NYU)
Title: Use and mention in formal languages

Abstract: Quine’s distinction between use and mention is one of the cornerstones of analytic philosophy. The distinction is typically motivated with examples from natural language, but Quine also applied the distinction to the formal languages studied in mathematical logic. I will argue that such expressions are not used in Quine’s sense, so the distinction cannot appropriately be applied to them. Accordingly, the standard practice of placing quotation marks around expressions of formal languages is incorrect. This technical point serves as a springboard for discussing the role that formal languages play in mathematical logic.



- - - - Tuesday, Dec 5, 2023 - - - -

Models of Peano Arithmetic (MOPA)
Tuesday, Dec 5, 1:00pm
Virtual (email Victoria Gitman vgitman@gmail.com for meeting id)
Mateusz Łełyk, University of Warsaw
Simplest model properties for Peano Arithmetic: On a question of Montalban and Rossegger



- - - - Wednesday, Dec 6, 2023 - - - -



- - - - Thursday, Dec 7, 2023 - - - -



- - - - Friday, Dec 8, 2023 - - - -

Model Theory Seminar
Friday, Dec 8, 12:30-2:00pm NY time, Room 5383
David Marker, University of Illinois at Chicago
Rigid real closed fields?

Every archimedean real closed field is rigid, i.e., has no nontrivial automorphisms. What happens in the non-archimedean case? Shelah showed it is consistent that there are uncountable rigid non-archimedean real closed fields. Enayat asked what happens in the countable case. I believe the question is even interesting in the finite transcendence degree case. In this talk I will describe Shelah's proof and discuss some interesting phenomenon that arises even in transcendence degree 2.




Logic Workshop
CUNY Graduate Center
Friday Dec 8, 2:00pm-3:30pm, Room 6417
Michael Benedikt, Oxford University
Beth definability and nested relations



- - - - Other Logic News - - - -



- - - - Web Site - - - -

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

--------  ADMINISTRIVIA  --------

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

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

Set Theory and Topology Seminar 28.11.2023 Jarosław Swaczyna

Wrocław Set Theory Seminar
I am happy to announce that at the seminar in Set Theory and Topology on Tuesday 28.11.2023 at 17:15 in room 601 (Mathematical Institute, University of Wrocław) the lecture:
"Zoo of ideal Schauder bases"

will be presented by

Jarosław Swaczyna (Łódź University of Technology)


Abstract.

Given a Banach space X, sequence (e_n) of its elements and an ideal I on natural numbers we say that (e_n) is an I-Schauder base if for every x \in X there exists unique sequence of scalars \alpha_n such that series of \alpha_n e_n is I-convergent to X. in such a case one may consider also coordinate functionals e_n^\star. About ten years ago Kadets asked if those functionals are necessarily continuous at least for some nice ideals, eg ideal of sets of density zero. During my talk I will present answer to this question obtained jointly with Tomasz Kania and Noe de Rancourt. I will also present some examples of ideal Schauder bases which are not the classical ones. Second part will be based on ongoing work with Adam Kwela.

Feel free to spread this information among Your colleagues.

I'm looking forward to seeing You
Szymon Żeberski

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

About 15 minutes before the seminar we invite you for coffee and a chat to social room.


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

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

Wednesday seminar

Prague Set Theory Seminar
Dear all, The seminar meets on Wednesday November 29th at 11:00 in the Institute of Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building. Program: Corey Switzer -- Reflecting Ordinals and Forcing Let $n < \omega$ and $\Gamma$ either $\Pi$ or $\Sigma$. An ordinal $\alpha$ is called $\Gamma^1_n$-reflecting if for each $\beta < \alpha$ and each $\Gamma^1_n$-formula $\varphi$ if $L_\alpha \models \varphi(\beta)$ then there is a $\gamma \in (\beta, \alpha)$ so that $L_\gamma \models \varphi(\beta)$ where here $\models$ refers to full second order logic. The least $\Sigma^1_n$-reflecting ordinal is called $\sigma^1_n$ and the least $\Pi^1_n$-ordinal is called $\pi^1_n$. These ordinals provably exist and are countable (for all $n < \omega$). These ordinals arise naturally in proof theory, particularly in calibrating consistency strength of strong arithmetics and weak set theories. Moreover, surprisingly, their relation to one another relies heavily on the background set theory. If $V=L$ then for all $n < \omega$ we have $\sigma^1_{n+3} < \pi^1_{n+3}$ (due to Cutland) while under PD for all $n < \omega$ we have $\sigma^1_n < \pi^1_n$ if and only if $n$ is even (due to Kechris). Surprisingly nothing was known about these ordinals in any model which satisfies neither $V=L$ nor PD. In this talk I will sketch some recent results which aim at rectifying this. In particular we will show that in any generic extension by any number of Cohen or Random reals, a Sacks, Miller or Laver real, or any lightface, weakly homogeneous Borel ccc forcing notion agrees with $L$ about which ordinals are $\Gamma^1_n$-reflecting (for any $n$ and $\Gamma$). Meanwhile, in the generic extension by collapsing $\omega_1$ many interesting things happen, not least amongst them that $\sigma^1_n$ and $\pi^1_n$ are increased - yet still below $\omega_1^L$ for $n > 2$. Along the way we will discuss the plethora of open problems in this area. This is joint work with Juan Aguilera. Best, David

(KGRC) videos, and the Set Theory Seminar talk this Thursday, November 23

Kurt Godel Research Center
The KGRC welcomes as guests: Serhii Bardyla visits the KGRC until November 24. Diego Alejandro Mejía visits the KGRC until January 31, 2024 and gives a second talk, see below: * * * Materials (video recordings, unless stated otherwise) available so far (starting from the beginning of October): October 5, D. Sobota, "Convergence in Banach spaces of measures and cardinal characteristics of the continuum, I": https://ucloud.univie.ac.at/index.php/s/OeIqEX2tRqEa2oP October 12, D. Sobota, "Convergence in Banach spaces of measures and cardinal characteristics of the continuum, II": https://ucloud.univie.ac.at/index.php/s/WmvEh0fgm4OEvQK October 12, R. Kossak, "Undefinability and Absolute Undefinability", video of speaker: https://ucloud.univie.ac.at/index.php/s/V00mfOUWXdgFytV video of slides: https://ucloud.univie.ac.at/index.php/s/hhHrKzzDpuF6G3S October 13, Š. Stejskalová, "Automorphisms of trees": https://ucloud.univie.ac.at/index.php/s/Ih99spR3b3wRomU October 13, L. Schembecker, "Peculiar maximal eventually different families": https://ucloud.univie.ac.at/index.php/s/EVgkWA741l763xU October 13, V. Fischer, "Splitting and bounding at the uncountable": https://ucloud.univie.ac.at/index.php/s/BlPjqyyqE6VzzL6 October 18, A. Bernshteyn, "The Local Lemma in descriptive combinatorics: a survey and recent developments": https://ucloud.univie.ac.at/index.php/s/6kLls3XchP64FSo October 19, D. Sobota, "Convergence in Banach spaces of measures and cardinal characteristics of the continuum, III": https://ucloud.univie.ac.at/index.php/s/SvYDRLOv7c7WPMI October 19, S. Lempp, "Spectra of Computable Models of Strongly Minimal Disintegrated Theories in Rank 1 Languages", video: https://ucloud.univie.ac.at/index.php/s/x5tRgUhjZ4rauDv slides: https://mathematik.univie.ac.at/fileadmin/user_upload/f_mathematik/Events_News/Vortraege_Events/2023-24/KGRC_Logic_Colloquium_2023-10-19_S._Lempp.pdf November 9, D. Sobota, "Convergence in Banach spaces of measures and cardinal characteristics of the continuum, IV": https://ucloud.univie.ac.at/index.php/s/CpkE5Ku9UiEJe2D November 9, D. Rossegger, "Structural complexity notions for foundational theories": https://ucloud.univie.ac.at/index.php/s/27tlQCsbpNWW79Q November 16, D. Sobota, "Convergence in Banach spaces of measures and cardinal characteristics of the continuum, V": https://ucloud.univie.ac.at/index.php/s/NXzwLDNnsJ31Sw3 * * * Set Theory Seminar Kurt Gödel Research Center Thursday, November 23 "Convergence in Banach spaces of measures and cardinal characteristics of the continuum, VI" Damian Sobota (KGRC) Mini-course (05.10.2023-23.11.2023, 6 lectures) - 6th lecture: I will discuss values of the cardinal characteristics of the continuum associated with the Nikodym and Grothendieck properties of Boolean algebras in various models of set theory. Time and Place Talk at 11:30am in hybrid mode: on-site as well as via Zoom Universität Wien Institut für Mathematik Kolingasse 14-16 1090 Wien 1st floor Seminar room 10 Zoom: If you have not received the Zoom data by the day before the talk, please contact richard.springer@univie.ac.at. Please direct any other questions about this talk to vera.fischer@univie.ac.at.

UPDATE: This Week in Logic at CUNY

This Week in Logic at CUNY
Two quick updates:
Tuesday's MOPA talk is at noon rather than 1pm.
Wednesday's Category Theory Seminar is cancelled.

All best,
Jonas

This Week in Logic at CUNY:

- - - - Monday, Nov 20, 2023 - - - -

Rutgers Logic Seminar
Monday, Nov 20, 3:30pm, Rutgers University, Hill 705
Alexei Miasnikov, Stevens Institute of Technology
First-order classification, non-standard models, and interpretations




Logic and Metaphysics Workshop
Date: Monday, Nov 20, 4.15-6.15pm (NY time)
Room: Graduate Center Room 4419

Marian Călborean (Bucharest).
Title: Vagueness and Frege

Abstract: A constant of Frege’s writing is his rejection of indeterminate predicates in natural language. I follow Frege’s remarks on vagueness from the early “Begriffsschrift” to his mature works, drawing parallels with contemporary theories of vagueness. I critically examine Frege’s arguments for the inconsistency of natural language and argue that the inability to accommodate vagueness and precision in his mature ontology and semantics is mainly due to heuristic rules which he took as essential, not to a deep problem in his fundamental apparatus.



- - - - Tuesday, Nov 21, 2023 - - - -

Models of Peano Arithmetic (MOPA)
Tuesday, Nov 21, 12:00pm
Virtual (email Victoria Gitman vgitman@gmail.com for meeting id)

Saeideh Bahrami, Institute for Research in Fundamental Sciences
-small submodels of countable models of arithmetic

There has been a long tradition in the model theory of arithmetic of attributing the combinatorial properties of cardinal numbers in set theory to initial segments. Considering that the most basic use of cardinal numbers is to assign cardinality to sets, we can adapt a similar notion in models of arithmetic in the following way: for a given initial segment  of any model  of a fragment of arithmetic, say I, a subset  of  is called I-small if there exists a coded bijection  in  such that the range of the restriction of  to  is equal to . It turns out that for a given countable nonstandard model  of I, when I is a strong cut, any -small -elementary submodel of  contains , and inherits some good properties of . In this talk, we are going to review such properties through self-embeddings of .





- - - - Wednesday, Nov 22, 2023 - - - -

The New York City Category Theory Seminar
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York
URL:  http://www.sci.brooklyn.cuny.edu/~noson/Seminar/index.html
Speaker:     Pedro Sota, TBA.
Date and Time:     Wednesday November 22, 2023, 7:00 - 8:30 PM. ZOOM TALK. CANCELLED



- - - - Thursday, Nov 23, 2023 - - - -

*** Graduate Center Closed (Thanksgiving) ***



- - - - Friday, Nov 24, 2023 - - - -

*** Graduate Center Closed (Thanksgiving) ***



Next Week in Logic at CUNY:

- - - - Monday, Nov 27, 2023 - - - -

Logic and Metaphysics Workshop
Date: Monday, Nov 20, 4.15-6.15pm (NY time)
Room: Graduate Center Room 4419
Mircea Dumitru (Bucharest).
Title: Truth with and without satisfaction

Abstract: The talk addresses a quite natural situation in mathematics. When one needs to define a concept and it is not possible to do a direct recursion on the concept itself, what one does is the next best thing which is to perform recursion on a related concept of which the original given concept can be shown to be a special case. Tarski, in his celebrated paper on “The Concept of Truth in Formalized Languages”, cannot give a definition of truth performing direct recursion on the concept of truth itself. Consequently, he settles on a definition in terms of satisfaction. Following Kit Fine and Timothy McCarthy, “Truth without Satisfaction”, I raise the issue of whether such an indirect procedure of giving a definition of truth is necessary or maybe an alternative definition of truth can be given without going through the related concept of satisfaction. My talk will investigate both certain technical and philosophical aspects of the two sets of formal constraints to defining truth with and without satisfaction.





- - - - Tuesday, Nov 28, 2023 - - - -



- - - - Wednesday, Nov 29, 2023 - - - -

The New York City Category Theory Seminar
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York
URL:  http://www.sci.brooklyn.cuny.edu/~noson/Seminar/index.html
Speaker:     Charlotte Aten, University of Denver.
Date and Time:     Wednesday November 29, 2023, 7:00 - 8:30 PM. ZOOM TALK.




- - - - Thursday, Nov 30, 2023 - - - -



- - - - Friday, Dec 1, 2023 - - - -

Model Theory Seminar
Friday, Dec 1, 12:30-2:00pm NY time, Room 5383

Rehana Patel Wesleyan University



Logic Workshop
CUNY Graduate Center
Friday Dec 1, 2:00pm-3:30pm, Room 6417
James Walsh New York University
Is the consistency operator canonical?



- - - - Other Logic News - - - -



- - - - Web Site - - - -

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

--------  ADMINISTRIVIA  --------

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

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

35th Nankai Logic Colloquium

Nankai Logic Colloquium

Hello everyone,

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

Our speaker this week will be Kazuyuki Tanaka from the Beijing Institute of Mathematical Sciences and Applications. This talk is going to take place this Friday, Nov 24, from 4pm to 5pm(UTC+8, Beijing time). 


Title: Reverse mathematics and infinite games in differences of ${\mathcal F}_\sigma$ sets

Abstract: Reverse mathematics is a foundational program which aims for answering the following questions: What set existence axioms are needed to prove the theorems of ordinary mathematics? Along this program, the strength of determinacy of infinite games of lower Borel sets has been extensively studied. In this talk, we would like to shed new light on the determinacy hierarchy over the boolean combinations of boldface $\Sigma^0_2$ sets. Among others, we show that such hierarchy collapses above boldface $\Sigma^0_2 \wedge \Pi^0_2$ sets, and the determinacy of boldface $\Delta(\Sigma^0_2 \wedge \Pi^0_2)$ turns out to be equivalent to that of boldface $\Sigma^0_2$. This is a joint work with W.Li and K.Yoshii. 

___________________________________________________________________________________________________________________________________________________


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

Title :The 35th Nankai Logic Colloquium --Kazuyuki Tanaka

Time :16:00pm, Nov. 24, 2023(Beijing Time)

Zoom Number :847 0296 7631

Passcode :547555

Link :https://zoom.us/j/84702967631?pwd=IApaBiX5Cqv58tVez39772LJdtHpfF.1

_____________________________________________________________________


Best wishes,

Ming Xiao




This Week in Logic at CUNY

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

- - - - Monday, Nov 20, 2023 - - - -

Rutgers Logic Seminar
Monday, Nov 20, 3:30pm, Rutgers University, Hill 705
Alexei Miasnikov, Stevens Institute of Technology
First-order classification, non-standard models, and interpretations




Logic and Metaphysics Workshop
Date: Monday, Nov 20, 4.15-6.15pm (NY time)
Room: Graduate Center Room 4419

Marian Călborean (Bucharest).
Title: Vagueness and Frege

Abstract: A constant of Frege’s writing is his rejection of indeterminate predicates in natural language. I follow Frege’s remarks on vagueness from the early “Begriffsschrift” to his mature works, drawing parallels with contemporary theories of vagueness. I critically examine Frege’s arguments for the inconsistency of natural language and argue that the inability to accommodate vagueness and precision in his mature ontology and semantics is mainly due to heuristic rules which he took as essential, not to a deep problem in his fundamental apparatus.



- - - - Tuesday, Nov 21, 2023 - - - -

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

Saeideh Bahrami, Institute for Research in Fundamental Sciences
-small submodels of countable models of arithmetic

There has been a long tradition in the model theory of arithmetic of attributing the combinatorial properties of cardinal numbers in set theory to initial segments. Considering that the most basic use of cardinal numbers is to assign cardinality to sets, we can adapt a similar notion in models of arithmetic in the following way: for a given initial segment  of any model  of a fragment of arithmetic, say I, a subset  of  is called I-small if there exists a coded bijection  in  such that the range of the restriction of  to  is equal to . It turns out that for a given countable nonstandard model  of I, when I is a strong cut, any -small -elementary submodel of  contains , and inherits some good properties of . In this talk, we are going to review such properties through self-embeddings of .





- - - - Wednesday, Nov 22, 2023 - - - -

The New York City Category Theory Seminar
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York
URL:  http://www.sci.brooklyn.cuny.edu/~noson/Seminar/index.html
Speaker:     Pedro Sota, TBA.
Date and Time:     Wednesday November 22, 2023, 7:00 - 8:30 PM. ZOOM TALK.



- - - - Thursday, Nov 23, 2023 - - - -

*** Graduate Center Closed (Thanksgiving) ***



- - - - Friday, Nov 24, 2023 - - - -

*** Graduate Center Closed (Thanksgiving) ***



Next Week in Logic at CUNY:

- - - - Monday, Nov 27, 2023 - - - -

Logic and Metaphysics Workshop
Date: Monday, Nov 20, 4.15-6.15pm (NY time)
Room: Graduate Center Room 4419
Mircea Dumitru (Bucharest).
Title: Truth with and without satisfaction

Abstract: The talk addresses a quite natural situation in mathematics. When one needs to define a concept and it is not possible to do a direct recursion on the concept itself, what one does is the next best thing which is to perform recursion on a related concept of which the original given concept can be shown to be a special case. Tarski, in his celebrated paper on “The Concept of Truth in Formalized Languages”, cannot give a definition of truth performing direct recursion on the concept of truth itself. Consequently, he settles on a definition in terms of satisfaction. Following Kit Fine and Timothy McCarthy, “Truth without Satisfaction”, I raise the issue of whether such an indirect procedure of giving a definition of truth is necessary or maybe an alternative definition of truth can be given without going through the related concept of satisfaction. My talk will investigate both certain technical and philosophical aspects of the two sets of formal constraints to defining truth with and without satisfaction.





- - - - Tuesday, Nov 28, 2023 - - - -



- - - - Wednesday, Nov 29, 2023 - - - -

The New York City Category Theory Seminar
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York
URL:  http://www.sci.brooklyn.cuny.edu/~noson/Seminar/index.html
Speaker:     Charlotte Aten, University of Denver.
Date and Time:     Wednesday November 29, 2023, 7:00 - 8:30 PM. ZOOM TALK.




- - - - Thursday, Nov 30, 2023 - - - -



- - - - Friday, Dec 1, 2023 - - - -

Model Theory Seminar
Friday, Dec 1, 12:30-2:00pm NY time, Room 5383

Rehana Patel Wesleyan University



Logic Workshop
CUNY Graduate Center
Friday Dec 1, 2:00pm-3:30pm, Room 6417
James Walsh New York University
Is the consistency operator canonical?



- - - - Other Logic News - - - -



- - - - Web Site - - - -

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

--------  ADMINISTRIVIA  --------

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

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

Set Theory and Topology Seminar 21.11.2023 Diego Mejia

Wrocław Set Theory Seminar
I am happy to announce that at the seminar in Set Theory and Topology on Tuesday 21.11.2023 at 17:15 in room 601 (Mathematical Institute, University of Wrocław) the lecture:
"Ultrafilters and finitely additive measures in forcing theory"

will be presented by

Diego Mejia (Shizuoka University)


Abstract.

We show how ultrafilters and finitely additive measures on the power set of the natural numbers can be used in forcing theory to construct models of ZFC where many classical cardinal characteristics have pairwise different values. Very recent remarkable results, like the consistency of Cichon's maximum (the constellation of Cichon's diagram where all non dependent cardinal characteristics are pairwise different), have been proved using such techniques.

Feel free to spread this information among Your colleagues.

I'm looking forward to seeing You
Szymon Żeberski

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

About 15 minutes before the seminar we invite you for coffee and a chat to social room.


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

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

Wednesday seminar

Prague Set Theory Seminar
Dear all, The seminar meets on Wednesday November 22nd at 11:00 in the Institute of Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building. Program: Lukas Schembecker -- Peculiar maximal eventually different families In my talk I will discuss a new notion of strong maximality for maximal eventually different families and explore some applications for the corresponding cardinal characteristic $\mathfrak{a}_e$ and its spectrum. ********************************************************************** Moreover, Jindra Zapletal will be giving a three lecture mini-course course "Geometric Set Theory" next week at IM PAN in Warsaw. The lectures will be broadcasted online and people are encouraged to join. The schedule is as follows: 20.11, Mon, 1:30-2:30pm, room 405 21.11, Tue, 12:30-1:30pm, room 405 22.11, Wed, 1:30-2:30pm, room 405 Link to the online streaming is: https://us02web.zoom.us/j/89366420630?pwd=c2hnTDhTelZiV3VCTWd4eG5oTlFlUT09 Abstract of the mini-course is in the attachment. Participants are encouraged to read about the Solovay model either from Jech's "Set Theory" (Millenium Edition) or Schindler's "Set Theory: Exploring Independence and Truth". However, this is not a necessary prerequisite, and the model will be introduced during the first lecture. You can contact Maciej Malicki with questions about the mini-course. Best, David

(KGRC) two seminar talks Thursday, November 16

Kurt Godel Research Center
Set Theory Seminar Kurt Gödel Research Center Thursday, November 16 "Convergence in Banach spaces of measures and cardinal characteristics of the continuum, V" Damian Sobota (KGRC) Mini-course (05.10.2023-23.11.2023, 6 lectures) - 5th lecture: I will continue studying upper and lower bounds for the cardinal characteristics of the continuum associated with the Nikodym and Grothendieck properties of Boolean algebras. Time and Place Talk at 11:30am in hybrid mode: on-site as well as via Zoom Universität Wien Institut für Mathematik Kolingasse 14-16 1090 Wien 1st floor Seminar room 10 Zoom: If you have not received the Zoom data by the day before the talk, please contact richard.springer@univie.ac.at. Please direct any other questions about this talk to vera.fischer@univie.ac.at. * * * Logic Colloquium Kurt Gödel Research Center Thursday, November 16 "Iterations with ultrafilter-limits and fam-limits" Diego Alejandro Mejía (Shizuoka U, JP) The method of finite support iterations with fams (finitely additive measures) on the power set of the natural numbers was first developed by Saharon Shelah (2000) to construct a model of ZFC where the cofinality of the covering of measure is countable. This type of iterations, as well as iterations with ultrafilter-limits, has played a fundamental role in recent work about the consistency of Cichon's maximum (with Kellner, Goldstern, and Shelah, also with Tanasie). In this talk, I present recent progress and generalizations of the technique of iterations with ultrafilter-limits and fam-limits, and its effect on some classical cardinal characteristics of the continuum, as developed in joint work with Brendle, Miguel Cardona, and Andrés Uribe-Zapata (as well as in work by Takashi Yamazoe). Time and Place Talk at 3:00pm in hybrid mode: on-site as well as via Zoom Universität Wien Institut für Mathematik Oskar-Morgenstern-Platz 1 1090 Wien 2nd floor room HS 11 Zoom: If you have not received the Zoom data by the day before the talk, please contact richard.springer@univie.ac.at. Please direct any other questions about this talk to vera.fischer@univie.ac.at.

This Week in Logic at CUNY

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

- - - - Monday, Nov 13, 2023 - - - -

Rutgers Logic Seminar
Monday, Nov 13, 3:30pm, Rutgers University, Hill 705
Paul Ellis, Rutgers
Finite Tukey Morphisms



Logic and Metaphysics Workshop
Date: Monday, Nov 13, 4.15-6.15pm (NY time)
Room: Graduate Center Room 4419

Alex Skiles (Rutgers).
Title: Against zero-grounding

Abstract: A number of philosophers believe that there is an intelligible distinction between ungrounded truths, which are not grounded in any truths at all, and zero-grounded truths, which are grounded, yet there are no truths that they are grounded in. Rather being a mere academic curiosity, these philosophers have also argued that the notion of zero-grounding can be put to serious metaphysical work. In this paper, we present two arguments against the intelligibility of zero-grounding, and then reject several attempts to make zero-grounding intelligible that have been suggested by its proponents.

Note: This is joint work with Tien-Chun Lo and Gonzalo Rodriguez-Pereyra.



- - - - Tuesday, Nov 14, 2023 - - - -

Models of Peano Arithmetic (MOPA)
Tuesday, Nov 14, 1:00pm
Virtual (email Victoria Gitman vgitman@gmail.com for meeting id)
Mengzhou Sun, National University of Singapore
On the (non)elementarity of cofinal extension

Compared with end extensions, much little is known about cofinal extensions for models of fragments of PA, especially their elementarity. In this talk, I will try to give a complete characterization of the elementarity of cofinal extensions. I will present a systematic way to `compress' the truth of M into the second-order structure of a definable cut, and as a consequence, a correspondence theorem between the first-order theory of M and the second-order theory of the cut. Through this method I will construct several models with special cofinal extension properties. I will also show that every countable model of arithmetic fail to satisfy PA admits a non-elementary cofinal extension. It provides a model-theoretic characterization for PA in terms of cofinal extensions.



- - - - Wednesday, Nov 15, 2023 - - - -



- - - - Thursday, Nov 16, 2023 - - - -



- - - - Friday, Nov 17, 2023 - - - -

Model Theory Seminar
Friday, Nov 17, 12:30-2:00pm NY time, Room 5383

Scott Mutchnik, University of Illinois at Chicago
 Theories

Among the classical properties of unstable theories defined by Shelah, our understanding of the strict order hierarchy, , has remained relatively limited past  at the greatest. Methods originating from stability theory have given insight into the structure of stronger unstable classes, including simple and  theories. In particular, syntactic information about formulas in a first-order theory often corresponds to semantic information about independence in a theory's models, which generalizes phenomena such as linear independence in vector spaces and algebraic independence in algebraically closed fields. We discuss how the fine structure of this independence reveals exponential behavior within the strict order hierarchy, particularly at the levels  for positive integers . Our results suggest a potential theory of independence for  theories, for arbitrarily large values of .




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

Joel David Hamkins, Notre Dame University
The Wordle and Absurdle numbers

We consider the game of infinite Wordle as played on Baire space . The codebreaker can win in finitely many moves against any countable dictionary , but not against the full dictionary of Baire space. The Wordle number is the size of the smallest dictionary admitting such a winning strategy for the codebreaker, the corresponding Wordle ideal is the ideal generated by these dictionaries, which under MA includes all dictionaries of size less than the continuum. The Absurdle number, meanwhile, is the size of the smallest dictionary admitting a winning strategy for the absurdist in the two-player variant, infinite Absurdle. In ZFC there are nondetermined Absurdle games, with neither player having a winning strategy, but if one drops the axiom of choice, then the principle of Absurdle determinacy has large cardinal consistency strength over ZF+DC. This is joint work with Ben De Bondt (Paris).




Next Week in Logic at CUNY:

- - - - Monday, Nov 20, 2023 - - - -

Rutgers Logic Seminar
Monday, Nov 20, 3:30pm, Rutgers University, Hill 705
Alexei Miasnikov, Stevens Institute of Technology




Logic and Metaphysics Workshop
Date: Monday, Nov 20, 4.15-6.15pm (NY time)
Room: Graduate Center Room 4419

Marian Călborean (Bucharest).

Title: Vagueness and Frege

Abstract: A constant of Frege’s writing is his rejection of indeterminate predicates in natural language. I follow Frege’s remarks on vagueness from the early “Begriffsschrift” to his mature works, drawing parallels with contemporary theories of vagueness. I critically examine Frege’s arguments for the inconsistency of natural language and argue that the inability to accommodate vagueness and precision in his mature ontology and semantics is mainly due to heuristic rules which he took as essential, not to a deep problem in his fundamental apparatus.



- - - - Tuesday, Nov 21, 2023 - - - -

Models of Peano Arithmetic (MOPA)
Tuesday, Nov 21, 1:00pm
Virtual (email Victoria Gitman vgitman@gmail.com for meeting id)
Saeideh Bahrami, Institute for Research in Fundamental Sciences



- - - - Wednesday, Nov 22, 2023 - - - -

The New York City Category Theory Seminar
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York
URL:  http://www.sci.brooklyn.cuny.edu/~noson/Seminar/index.html
Speaker:     Pedro Sota, TBA.
Date and Time:     Wednesday November 22, 2023, 7:00 - 8:30 PM. ZOOM TALK.



- - - - Thursday, Nov 23, 2023 - - - -

*** Graduate Center Closed (Thanksgiving) ***



- - - - Friday, Nov 24, 2023 - - - -

*** Graduate Center Closed (Thanksgiving) ***



- - - - Other Logic News - - - -

MEMORIAL FOR DAVISES (forwarded from the FOM list):
Dear FOM,

I've been asked to post an announcement for a special event in memory of Martin and Virginia Davis to be held at the Courant Institute (NYU) on January 26, 2024. Martin Davis was a long-time moderator for FOM. The web page for the event is at
https://cims.nyu.edu/dynamic/conferences/davis-memorial/
The event plans presentations by Allyn Jackson, Eugenio Omodeo and Wilfried Sieg and a session on Memories of Martin and Virginia Davis. 

If you will attend, the organizers request you preregister online so that they can reserve an appropriate room and arrange for building access. The event will also be livestreamed.

People who cannot attend in person may submit a paragraph or two to the organizers to be read aloud at the event.



- - - - Web Site - - - -

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

--------  ADMINISTRIVIA  --------

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

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

Set Theory and Topology Seminar 14.11.2023 Aleksander Cieślak

Wrocław Set Theory Seminar

Szymon Żeberski szymon.zeberski@pwr.edu.pl

sob., 4 lis, 10:22 (8 dni temu)
do UDW: akwiatkowska314@gmail.com, UDW: aleksanderdxpody@gmail.com, UDW: Artsiom, UDW: Bartosz, UDW: Daria, UDW: Dominik, UDW: grzegorz.plebanek@math.uni.wroc.pl, UDW: Igor, UDW: ivanov@math.uni.wroc.pl, UDW: Jacek, UDW: jan.kraszewski@math.uni.wroc.pl, UDW: janusz.pawlikowski@math.uni.wroc.pl, UDW: Jeremiasz, UDW: Joanna, UDW: jswaczyna@wp.pl, UDW: Karina, UDW: Korpalski, UDW: Krzysztof, UDW: Krzysztof, UDW: krzysztof.omiljanowski@math.uni.wroc.pl, UDW: lipecki@impan.gov.pl, UDW: Marcin, UDW: Martinez, UDW: Michał, UDW: Michał, UDW: Michał, UDW: Migacz, UDW: Morawski, UDW: nikiel@uni.opole.pl, UDW: Paweł, UDW: pborod@math.uni.wroc.pl, UDW: rafal.filipow@mat.ug.edu.pl, UDW: Robert, UDW: Robert, UDW: Sebastian, UDW: sebastian.jachimek@math.uni.wroc.pl, UDW: settheorytalks@gmail.com, UDW: mnie, UDW: Szymon, UDW: tomasz.zuchowski@math.uni.wroc.pl, UDW: Widz, UDW: Witold, UDW: Łukasz
I am happy to announce that at the seminar in Set Theory and Topology on Tuesday 14.11.2023 at 17:15 in room 601 (Mathematical Institute, University of Wrocław) the lecture:
"Cofinalities of tree ideals and the shrinking property II"

will be presented by

Aleksander Cieślak


Abstract.

Last time, given a tree type \TT, we investigated a cardinal invariant is(\TT) called "Incompatibility Shrinking Number". It was mentioned that the assumption is(\TT)=\continuum implies that    cof(t^0)>\continuum and that is(\TT) falls in between the additivity and the covering number of the borel part t^0_Bor. We will focus on calculating these two for various Borel ideals.


Feel free to spread this information among Your colleagues.

I'm looking forward to seeing You
Szymon Żeberski

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

About 15 minutes before the seminar we invite you for coffee and a chat to social room.


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

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

Nankai Logic Colloquium

Nankai Logic Colloquium

Hello everyone,

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

Our speaker this week will be Marcin Sabok from McGill University. This talk is going to take place this Friday, Nov 17, from 9am to 10am(UTC+8, Beijing time). 

Title:
Finding the patterns {x,y,xy,x+y} in colorings of the rationals.

Abstract:
We show that for every coloring of the rationals into finitely many colors, one of the colors contains a set of the form  {x,y,xy,x+yfor some nonzero x and y. Joint work with Matt Bowen

Thank you! I look forward to seeing you next week!

___________________________________________________________________________________________________________________________________________________


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

Title :The 34th Nankai Logic Colloquium --Marcin Sabok

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

Zoom Number :872 7448 5609

Passcode :448066

Link :https://zoom.us/j/87274485609?pwd=z90Pn2KFasUa3KbbvQ1d7xSl3eP6rc.1

_____________________________________________________________________


Best wishes,

Ming Xiao






(KGRC) two talks tomorrow, Thursday, November 9

Kurt Godel Research Center
Set Theory Seminar Kurt Gödel Research Center Thursday, November 9 "Convergence in Banach spaces of measures and cardinal characteristics of the continuum, IV" Damian Sobota (KGRC) Mini-course (05.10.2023-23.11.2023, 6 lectures) - 4th lecture: During my 4th talk I'll continue to describe connections between complexity of filters on omega and convergence of finitely supported measures on spaces of the form $N_F=\omega\cup\{F\}$. I'll also show how to relate cardinal characteristics of the continuum to the Grothendieck property and the Nikodym property of Boolean algebras and provide various estimates for them in terms of standard cardinal characteristics from Cichoń's diagram. Time and Place Talk at 11:30am in hybrid mode: on-site as well as via Zoom Universität Wien Institut für Mathematik Kolingasse 14-16 1090 Wien 1st floor Seminar room 10 Zoom: If you have not received the Zoom data, please contact richard.springer@univie.ac.at. Please direct any other questions about this talk to vera.fischer@univie.ac.at. * * * Set Theory Seminar Kurt Gödel Research Center Thursday, November 9 "Structural complexity notions for foundational theories" Dino Rossegger (TU Wien) I will report on a couple of projects investigating the "structural complexity" of models of first-order theories with foundational character. In a project with Antonio Montalbán, we performed a Scott analysis of models of Peano arithmetic and showed, in layperson's terms, that nonstandard models of arithmetic cannot be simple. More formally, our main result shows that every completion of PA has models of Scott rank alpha for every infinite Scott rank alpha. However, the standard model is the unique model of PA with finite Scott rank. In other work with Uri Andrews and Steffen Lempp, we give a characterization of first-order theories that have a boldface Pi^0_omega complete set of models. As a corollary, we obtain that all sequential theories have a Pi^0_omega complete set of models. At last, I will talk about a new project with Darius Kalociński and Mateusz Łełyk that aims to generalize and improve the results obtained with Montalbán. Time and Place Talk at 3:00pm in hybrid mode: on-site as well as via Zoom Universität Wien Institut für Mathematik Oskar-Morgenstern-Platz 1 1090 Wien 2nd floor room HS 11 Zoom: If you have not received the Zoom data, please contact richard.springer@univie.ac.at. Please direct any other questions about this talk to vera.fischer@univie.ac.at.

This Week in Logic at CUNY

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

- - - - Monday, Nov 6, 2023 - - - -

Logic and Metaphysics Workshop
Date: Monday, Nov 6, 4.15-6.15pm (NY time)
Room: Graduate Center Room 4419

Alex Citkin (Metropolitan Telecommunications).
Title: On logics of acceptance and rejection

Abstract: In his book Formalization of Logic, Carnap suggested the following process of refutation: for any set of formulas Γ and any formula α, if Γ ⊢ α and α is rejected, reject Γ. Thus, in contrast to the Łukasiewicz’s approach to refutation, the predicate of rejection is defined on sets of formulas rather than just formulas. In addition to a predicate of rejection, we introduce a predicate of acceptance which is also defined on sets of formulas, and this leads us to constructing two-layered logical systems, the ground layer of which is a conventional deductive system (providing us with means for derivation), and the top layer having predicates of acceptance and rejection. In the case when the set of accepted formulas coincides with the set of theorems of the underlying logic and the set of rejected formulas coincides with the sets of non-theorems, we obtain a conventional deductive system. The predicate of acceptance can be non-adjunctive, and this allows us to use such systems as an alternative approach to defining Jaśkowski style discursive logics.




- - - - Tuesday, Nov 7, 2023 - - - -

Models of Peano Arithmetic (MOPA)
Tuesday, Nov 7, 1:00pm
Virtual (email Victoria Gitman vgitman@gmail.com for meeting id)
Stefan Hetzl, Vienna University of Technology

This talk is about the relationship between (weak) arithmetical theories and methods for automated inductive theorem proving. Automating the search for proofs by induction is an important topic in computer science with a history that stretches back decades. A variety of different approaches, algorithms and implementations has been developed.

In this talk I will present a logical approach for understanding the power and limits of methods for automated inductive theorem proving. A central tool are translations of proof systems that are intended for automated proof search into weak arithmetical theories. Another central tool are non-standard models of these weak arithmetical theories.

This approach allows to obtain independence results which are of practical interest in computer science. It also gives rise to a number of new problems and questions about weak arithmetical theories.




- - - - Wednesday, Nov 8, 2023 - - - -

Philog Seminar
The Graduate Center of The City University of New York
November 8, 2023, Wednesday, 10 AM
Zoom meeting, please contact Rohit Parikh for zoom link
Robert Stalnaker (MIT)
Conversational strategy and political discourse



The New York City Category Theory Seminar
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York
URL:  http://www.sci.brooklyn.cuny.edu/~noson/Seminar/index.html

Speaker:     Larry Moss, Indiana University, Bloomington .

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

Title:     On Kripke, Vietoris, and Hausdorff Polynomial Functors.


Abstract: The Vietoris space of compact subsets of a given Hausdorff space yields an endofunctor V on the category of Hausdorff spaces. Vietoris polynomial endofunctors on that category are built from V, the identity and constant functors by forming products, coproducts and compositions. These functors are known to have terminal coalgebras and we deduce that they also have initial algebras. We present an analogous class of endofunctors on the category of extended metric spaces, using in lieu of V the Hausdorff functor H. We prove that the ensuing Hausdorff polynomial functors have terminal coalgebras and initial algebras. Whereas the canonical constructions of terminal coalgebras for Vietoris polynomial functors takes omega steps, one needs \omega + \omega steps in general for Hausdorff ones. We also give a new proof that the closed set functor on metric spaces has no fixed points.




- - - - Thursday, Nov 9, 2023 - - - -



- - - - Friday, Nov 10, 2023 - - - -

Model Theory Seminar
Friday, Nov 10, 12:30-2:00pm NY time, Room 5383
Alexander Van Abel Wesleyan University

Asymptotics of the Spencer-Shelah Random Graph Sequence

In combinatorics, the Spencer-Shelah random graph sequence is a variation on the independent-edge random graph model. We fix an irrational number , and we probabilistically generate the n-th Spencer-Shelah graph (with parameter ) by taking  vertices, and for every pair of distinct vertices, deciding whether they are connected with a biased coin flip, with success probability . On the other hand, in model theory, an -mac is a class of finite structures, where the cardinalities of definable subsets are particularly well-behaved. In this talk, we will introduce the notion of 'probabalistic -mac' and present an incomplete proof that the Spencer Shelah random graph sequence is an example of one.



Logic Workshop
CUNY Graduate Center
Friday Nov 10, 2:00pm-3:30pm, Room 6417

Victoria Gitman, CUNY
Upward Löwenheim Skolem numbers for abstract logics

Galeotti, Khomskii and Väänänen recently introduced the notion of the upward Löwenheim Skolem (ULS) number for an abstract logic. A cardinal  is the upward Lowenheim Skolem number for a logic  if it is the least cardinal with the property that whenever  is a model of size at least  satisfying a sentence  in , then there are arbitrarily large models  satisfying  and having  as a substructure (not necessarily elementary). If we remove the requirement that  has to be a substructure of , we get the classic notion of a Hanf number. While  proves that every logic has a Hanf number, having a ULS number often turns out to have large cardinal strength. In a joint work with Jonathan Osinski, we study the ULS numbers for several classical logics. We introduce a strengthening of the ULS number, the strong upward Löwenheim Skolem number SULS which strengthens the requirement that  is a substructure to full elementarity in the logic . It is easy to see that both the ULS and the SULS number for a logic  are bounded by the least strong compactness cardinal for , if it exists.



Next Week in Logic at CUNY:

- - - - Monday, Nov 13, 2023 - - - -

Rutgers Logic Seminar
Monday, Nov 13, 3:30pm, Rutgers University, Hill 705
Paul Ellis, Rutgers
Finite Tukey Morphisms


Logic and Metaphysics Workshop
Date: Monday, Nov 13, 4.15-6.15pm (NY time)
Room: Graduate Center Room 4419

Alex Skiles (Rutgers).
Title: Against zero-grounding

Abstract: A number of philosophers believe that there is an intelligible distinction between ungrounded truths, which are not grounded in any truths at all, and zero-grounded truths, which are grounded, yet there are no truths that they are grounded in. Rather being a mere academic curiosity, these philosophers have also argued that the notion of zero-grounding can be put to serious metaphysical work. In this paper, we present two arguments against the intelligibility of zero-grounding, and then reject several attempts to make zero-grounding intelligible that have been suggested by its proponents.

Note: This is joint work with Tien-Chun Lo and Gonzalo Rodriguez-Pereyra.


- - - - Tuesday, Nov 14, 2023 - - - -

Models of Peano Arithmetic (MOPA)
Tuesday, Nov 14, 1:00pm
Virtual (email Victoria Gitman vgitman@gmail.com for meeting id)
Mengzhou Sun, National University of Singapore
On the (non)elementarity of cofinal extension

Compared with end extensions, much little is known about cofinal extensions for models of fragments of PA, especially their elementarity. In this talk, I will try to give a complete characterization of the elementarity of cofinal extensions. I will present a systematic way to `compress' the truth of M into the second-order structure of a definable cut, and as a consequence, a correspondence theorem between the first-order theory of M and the second-order theory of the cut. Through this method I will construct several models with special cofinal extension properties. I will also show that every countable model of arithmetic fail to satisfy PA admits a non-elementary cofinal extension. It provides a model-theoretic characterization for PA in terms of cofinal extensions.



- - - - Wednesday, Nov 15, 2023 - - - -



- - - - Thursday, Nov 16, 2023 - - - -



- - - - Friday, Nov 17, 2023 - - - -

Logic Workshop
CUNY Graduate Center
Friday Nov 17, 2:00pm-3:30pm, Room 6417
Joel David Hamkins Notre Dame University




- - - - Other Logic News - - - -


- - - - Web Site - - - -

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

--------  ADMINISTRIVIA  --------

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

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Set Theory and Topology Seminar 7.11.2023 Zdenek Silber

Wrocław Set Theory Seminar
I am happy to announce that at the seminar in Set Theory and Topology on Tuesday 7.11.2023 at 17:15 in room 601 (Mathematical Institute, University of Wrocław) the lecture:
"A countably tight P(K) space admitting a nonseparable measure"

will be presented by

Zdenek Silber (IM PAN)


Abstract.

In the talk we focus on the relation of countable tightness of the space P(K) of Radon probabilty measures on a compact Hausdorff space K and of existence of measures in P(K) that have uncountable Maharam type. Recall that a topological space X has countable tightness if any element of the closure of a subset A of X lies in the closure of some countable subset of A. A Maharam type of a Radon probability measure mu is the density of the Banach space L1(mu).
It was proven by Fremlin that, under Martin's axiom and negation of continuum hypothesis, for a compact Hausdorff space K the existance of a Radon probability of uncountable type is equivalent to the exitence of a continuous surjection from K onto [0,1]^omega1. Hence, under such assumptions, countable tightness of P(K) implies that there is no Radon probability on K which has uncountable type. Later, Plebanek and Sobota showed that, without any additional set-theoretic assumptions, countable tightness of P(KxK) implies that there is no Radon probability on K which has uncountable type as well. It is thus natural to ask whether the implication "P(K) has countable tightness implies every Radon probability on K has countable type" holds in ZFC.
I will present our joint result with Piotr Koszmider that under diamond principle there is a compact Hausdorff space K such that P(K) has countable tightness but there exists a Radon probability on K of uncountable type.

Feel free to spread this information among Your colleagues.

I'm looking forward to seeing You
Szymon Żeberski

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

About 15 minutes before the seminar we invite you for coffee and a chat to social room.


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

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


Wednesday seminar

Prague Set Theory Seminar
Dear all, There will be no Wednesday seminar next week November 8th due to the open days of the Institute in Zitna. The seminar on Wednesday November 15th is also cancelled as people will go away for conferences that week. The seminar should meet again on Wednesday November 22nd for a talk of Lukas Schembecker. Best, David

Set Theory and Topology Seminar 3.11.2023 Witold Marciszewski

Wrocław Set Theory Seminar
I am happy to announce that at the (EXTRA) seminar in Set Theory and Topology on Friday 3.11.2023 at 16:15 in room 60x (Mathematical Institute, University of Wrocław) the lecture:
"On \omega-Corson compact spaces and related classes of Eberlein compacta"
will be presented by
Witold Marciszewski (MIM UW)

We meet at the coffee place around 16.00 as usual.
Please write to grzegorz.plebanek@math.uni.wroc.pl if you feel like going to Woo Thai after the seminar.

Abstract:
Recall that a compact space K is Eberlein compact if it can be embedded into some Banach space X equipped with the weak topology; equivalently, for some set \Gamma, K can be embedded into the space c_0( \Gamma), endowed with the pointwise convergence topology.
A compact space K is \omega-Corson compact if, for some set \Gamma, K is homeomorphic to a subset of the \sigma-product of real lines \sigma(R^\Gamma), i.e. the subspace of the product R^\Gamma consisting of functions with finite supports. Clearly, every \omega-Corson compact space is Eberlein compact.
We will present a characterization of \omega-Corson compact spaces, and some other results concerning this class of spaces and related classes of Eberlein compacta.
This is a joint research with Grzegorz Plebanek and Krzysztof Zakrzewski, see
https://arxiv.org/abs/2107.02513

Feel free to spread this information among Your colleagues.

I'm looking forward to seeing You
Szymon Żeberski

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

About 15 minutes before the seminar we invite you for coffee and a chat to social room.


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

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

Wednesday seminar

Prague Set Theory Seminar
Dear all, The seminar meets on Wednesday November 1st at 11:00 in the Institute of Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building. Program: Christian Pech -- Homogeneous ultrametric structures (towards two-dimensional Fraısse theory) Abstract attached. Best, David

Cross-Alps Logic Seminar (speaker: Steffen Lempp)

Cross-Alps Logic Seminar
On Friday 03.11.2023 at 16:00

Steffen Lempp (University of Wisconsin)

will give a talk on

The complexity of the class of models of arithmetic

Please refer to the usual webpage of our LogicGroup for more details and the abstract of the talk.

The seminar will be held remotely through Webex. Please write to luca.mottoros [at] unito [dot] itfor the link to the event.

The Cross-Alps Logic Seminar is co-organized by the logic groups of Genoa, Lausanne, Turin and Udine as part of our collaboration in the project PRIN 2022 'Models, Sets and Classifications'.



Privo di virus.www.avast.com

Cross-Alps Logic Seminar (speaker: Steffen Lempp)

Cross-Alps Logic Seminar
On Friday 03.11.2023 at 16.00
Steffen Lempp (University of Wisconsin)
will give a talk on 
The complexity of the class of models of arithmetic

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

The Cross-Alps Logic Seminar is co-organized by the logic groups of Genoa, Lausanne, Turin and Udine as part of our collaboration in the project PRIN 2022 'Models, Sets and Classifications'.

All the best,
Vincenzo

This Week in Logic at CUNY

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

- - - - Monday, Oct 30, 2023 - - - -

Rutgers Logic Seminar
Monday, Oct 30th, 3:30pm, Rutgers University, Hill 705
Filippo Calderoni, Rutgers
Condensation and solvable left-orderable groups


Logic and Metaphysics Workshop
Date: Monday, Oct 30, 4.15-6.15pm (NY time)
Room: Graduate Center Room 4419
Brad Armour-Garb (SUNY Albany).
Title: An approach to property-talk for property nominalists

Abstract: Properties, understood as immanent universals that are repeatable entities which distinct objects can each have at the same time and in different places, are weird, so weird, in fact, that if we could do without them, we probably should do so. An alternative to an approach that sanctions properties might suggest a deflationary view of property-talk according to which the raison d’être of our use of ‘property’ is that it serves a quasi-logical function that is akin to what alethic deflationists claim about truth-talk. Deflationists about property-talk normally subscribe to a form of property nominalism, which rejects the sort of property realism that takes properties to be immanent universals. In this talk, after highlighting some of the weirdness of, or worries for, property realism and explaining why certain forms of property nominalism should not be abided, I highlight the expressive role of property-talk and go on to explain how property-talk performs its roles by introducing what I call “adjectival predicate-variable deflationism” (“APVD”). As I will show, by incorporating APVD into a version of what I have called a “semantic-pretense involving fictionalism” (“SPIF”), we capture the full range of property-talk instances without compromising property nominalism. Time permitting, I will also highlight a virtue of my view, which another form of property nominalism cannot accommodate. If property nominalism is correct, then we should endorse the SPIF account of property-talk that I will develop in this talk.

Note: This is joint work with James A. Woodbridge.




- - - - Tuesday, Oct 31, 2023 - - - -



- - - - Wednesday, Nov 1, 2023 - - - -



- - - - Thursday, Nov 2, 2023 - - - -



- - - - Friday, Nov 3, 2023 - - - -

Model Theory Seminar
Friday, Nov 3, 12:30-2:00pm NY time, Room 5383
Alfred Dolich CUNY
Definable sets in rank two expansions of ordered groups

I will discuss work on burden 2 or dp-rank 2 expansions of theories of densely ordered Abelian groups. Such theories allow for some variety in the topological properties of definable subsets in their models and I'll discuss how diverse the collection of definable subsets in a model may be. For example, is it possible to simultaneously define an infinite discrete set and a dense co-dense subset? Answers to such questions often hinge on whether one is working in the inp-rank or dp-rank case (i.e. whether one assumes NIP or not). I will provide definitions in the talk of all the relevant notions. This is joint work with John Goodrick.



Logic Workshop
CUNY Graduate Center
Friday Nov 3, 2:00pm-3:30pm, Room 6417
Karel Hrbacek, CUNY
Nonstandard methods without the Axiom of Choice

Model-theoretic frameworks for nonstandard methods entail the existence of nonprincipal ultrafilters over N, a strong version of the Axiom of Choice (AC). While AC is instrumental in many abstract areas of mathematics, such as general topology or functional analysis, its use in infinitesimal calculus or number theory should not be necessary.

Mikhail Katz and I have formulated a set theory SPOT in the language that has, in addition to membership, a unary predicate “is standard.” In addition to ZF, the theory has three simple axioms, Transfer, Nontriviality and Standard Part, that reflect the insights of Leibniz. It is a subtheory of the nonstandard set theories IST and HST, but unlike them, it is a conservative extension of ZF. Arguments carried out in SPOT thus do not depend on any form of AC. Infinitesimal calculus can be developed in SPOT as far as the global version of Peano's Theorem (the usual proofs of which use ADC, the Axiom of Dependent Choice). The existence of upper Banach densities can be proved in SPOT.

The conservativity of SPOT over ZF is established by a construction that combines the methods of forcing developed by Ali Enayat for second-order arithmetic and Mitchell Spector for set theory with large cardinals.

A stronger theory SCOT is a conservative extension of ZF+ADC. It is suitable for handling such features as an infinitesimal approach to the Lebesgue measure.

I will also formulate an extension of SPOT to a theory with multiple levels of standardness SPOTS, in which Renling Jin's recent groundbreaking proof of Szemeredi's Theorem can be carried out. While it is an open question whether SPOTS is conservative over ZF, SPOTS + DC (Dependent Choice for relations definable in it) is a conservative extension of ZF + ADC.

Reference: KH and M. G. Katz, Infinitesimal analysis without the Axiom of Choice, Ann. Pure Applied Logic 172, 6 (2021). https://doi.org/10.1016/j.apal.2021.102959https://arxiv.org/abs/2009.04980 






Next Week in Logic at CUNY:

- - - - Monday, Nov 6, 2023 - - - -

Logic and Metaphysics Workshop
Date: Monday, Nov 6, 4.15-6.15pm (NY time)
Room: Graduate Center Room 4419

Alex Citkin (Metropolitan Telecommunications).
Title: On logics of acceptance and rejection

Abstract: In his book Formalization of Logic, Carnap suggested the following process of refutation: for any set of formulas Γ and any formula α, if Γ ⊢ α and α is rejected, reject Γ. Thus, in contrast to the Łukasiewicz’s approach to refutation, the predicate of rejection is defined on sets of formulas rather than just formulas. In addition to a predicate of rejection, we introduce a predicate of acceptance which is also defined on sets of formulas, and this leads us to constructing two-layered logical systems, the ground layer of which is a conventional deductive system (providing us with means for derivation), and the top layer having predicates of acceptance and rejection. In the case when the set of accepted formulas coincides with the set of theorems of the underlying logic and the set of rejected formulas coincides with the sets of non-theorems, we obtain a conventional deductive system. The predicate of acceptance can be non-adjunctive, and this allows us to use such systems as an alternative approach to defining Jaśkowski style discursive logics.




- - - - Tuesday, Nov 7, 2023 - - - -

Models of Peano Arithmetic (MOPA)
Tuesday, Nov 7, 1:00pm
Virtual (email Victoria Gitman vgitman@gmail.com for meeting id)
Stefan Hetzl, Vienna University of Technology



- - - - Wednesday, Nov 8, 2023 - - - -

The New York City Category Theory Seminar
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York
URL:  http://www.sci.brooklyn.cuny.edu/~noson/Seminar/index.html

Speaker:     Larry Moss, Indiana University, Bloomington .

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

Title:     On Kripke, Vietoris, and Hausdorff Polynomial Functors.


Abstract: The Vietoris space of compact subsets of a given Hausdorff space yields an endofunctor V on the category of Hausdorff spaces. Vietoris polynomial endofunctors on that category are built from V, the identity and constant functors by forming products, coproducts and compositions. These functors are known to have terminal coalgebras and we deduce that they also have initial algebras. We present an analogous class of endofunctors on the category of extended metric spaces, using in lieu of V the Hausdorff functor H. We prove that the ensuing Hausdorff polynomial functors have terminal coalgebras and initial algebras. Whereas the canonical constructions of terminal coalgebras for Vietoris polynomial functors takes omega steps, one needs \omega + \omega steps in general for Hausdorff ones. We also give a new proof that the closed set functor on metric spaces has no fixed points.




- - - - Thursday, Nov 9, 2023 - - - -



- - - - Friday, Nov 10, 2023 - - - -

Model Theory Seminar
Friday, Nov 10, 12:30-2:00pm NY time, Room 5383
Alexander Van Abel Wesleyan University


Logic Workshop
CUNY Graduate Center
Friday Nov 10, 2:00pm-3:30pm, Room 6417

Victoria Gitman, CUNY
Upward Löwenheim Skolem numbers for abstract logics

Galeotti, Khomskii and Väänänen recently introduced the notion of the upward Löwenheim Skolem (ULS) number for an abstract logic. A cardinal  is the upward Lowenheim Skolem number for a logic  if it is the least cardinal with the property that whenever  is a model of size at least  satisfying a sentence  in , then there are arbitrarily large models  satisfying  and having  as a substructure (not necessarily elementary). If we remove the requirement that  has to be a substructure of , we get the classic notion of a Hanf number. While  proves that every logic has a Hanf number, having a ULS number often turns out to have large cardinal strength. In a joint work with Jonathan Osinski, we study the ULS numbers for several classical logics. We introduce a strengthening of the ULS number, the strong upward Löwenheim Skolem number SULS which strengthens the requirement that  is a substructure to full elementarity in the logic . It is easy to see that both the ULS and the SULS number for a logic  are bounded by the least strong compactness cardinal for , if it exists.




- - - - Other Logic News - - - -


- - - - Web Site - - - -

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

--------  ADMINISTRIVIA  --------

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

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

Set Theory and Topology Seminar 31.10.2023 Aleksander Cieślak

Wrocław Set Theory Seminar
I am happy to announce that at the seminar in Set Theory and Topology on Tuesday 31.10.2023 at 17:15 in room 601 (Mathematical Institute, University of Wrocław) the lecture:
"Cofinalities of tree ideals and Shrinking Property"

will be presented by

Aleksander Cieślak


Abstract.

If \mathcal{T} is a collection of trees on \Baire, then we define the tree ideal t_0 as a collection of these X\subset \Baire such that each T\in \mathcal{T} has a subtree S\in \mathcal{T} which shares no branches with X. We will be interested in the cofinalities of the tree ideals. In particular, we will focus on the condition, called "Incompatibility Shrinking Property", which implies that cof(t_0)>\continuum. We will consider under what assumptions this property is satisfied for the two types of trees, which are Laver and Miller trees which split positively according to some fixed ideal on \omega.


Feel free to spread this information among Your colleagues.

I'm looking forward to seeing You
Szymon Żeberski

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

About 15 minutes before the seminar we invite you for coffee and a chat to social room.


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

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

Wednesday seminar

Prague Set Theory Seminar
Dear all, The seminar meets on Wednesday October 25th at 11:00 in the Institute of Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building. The program is to be be determined. In case anybody is interested in giving a talk, let me know. Best, David

This Week in Logic at CUNY

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

- - - - Monday, Oct 23, 2023 - - - -

Rutgers Logic Seminar
Monday, Oct 23rd, 3:30pm, Rutgers University, Hill 705
Forte Shinko, Berkeley
Equivalence relations classifiable by actions of Polish abelian groups



Logic and Metaphysics Workshop
Date: Monday, Oct 23, 4.15-6.15pm (NY time)
Room: Graduate Center Room 4419

Melissa Fusco (Columbia)
Title: Diachronic reasoning with conditionals

Abstract: I will discuss a hybrid decision theory, coinciding sometimes with (traditional) Evidential Decision Theory, but usually with (traditional) Causal Decision Theory, which is inspired by recent work on unified and fully compositional approaches to the probabilities of conditionals. The hybrid theory features a few other loci of interest: the partitionality of acts A ∈ {A} fails, and close attention is paid to how one might (dis)confirm chance hypotheses under the umbrella of the Principal Principle. On this theory, the probabilities of conditionals play a role in underwriting a theory of imaging that follows Skyrms’s Thesis (Skyrms, 1981, 1984). Moreover, the credences it is epistemically rational to assign to these conditionals guides updating on one’s own acts. This implies some departures from Conditionalization, which I defend on epistemological grounds.




- - - - Tuesday, Oct 24, 2023 - - - -

Models of Peano Arithmetic (MOPA)
Tuesday, Oct 24, 1:00pm
Virtual (email Victoria Gitman vgitman@gmail.com for meeting id)

Alessandro Berarducci and Marcello Mamino, University of Pisa
Provability logic: models within models in Peano Arithmetic

In 1994 Jech gave a model theoretic proof of Gödel's second incompleteness theorem for Zermelo-Fraenkel set theory in the following form: ZF does not prove that ZF has a model. Kotlarski showed that Jech's proof can be adapted to Peano Arithmetic with the role of models being taken by complete consistent extensions. In this note we take another step in the direction of replacing proof-theoretic by model-theoretic arguments. We show, without passing through the arithmetized completeness theorem, that the existence of a model of PA of complexity  is independent of PA, where a model is identified with the set of formulas with parameters which hold in the model. Our approach is based on a new interpretation of the provability logic of Peano Arithmetic with the modal operator interpreted as truth in every -model.



- - - - Wednesday, Oct 25, 2023 - - - -

The New York City Category Theory Seminar
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York
URL:  http://www.sci.brooklyn.cuny.edu/~noson/Seminar/index.html

Speaker:     Emilio Minichiello, CUNY Graduate Center.

Date and Time:     Wednesday October 25, 2023, 7:00 - 8:30 PM. IN PERSON TALK (GC 6417)

Title:     A Mathematical Model of Package Management Systems.


Abstract: In this talk, I will review some recent joint work with Gershom Bazerman and Raymond Puzio. The motivation is simple: provide a mathematical model of package management systems, such as the Hackage package respository for Haskell, or Homebrew for Mac users. We introduce Dependency Structures with Choice (DSC) which are sets equipped with a collection of possible dependency sets for every element and satisfying some simple conditions motivated from real life use cases. We define a notion of morphism of DSCs, and prove that the resulting category of DSCs is equivalent to the category of antimatroids, which are mathematical structures found in combinatorics and computer science. We analyze this category, proving that it is finitely complete, has coproducts and an initial object, but does not have all coequalizers. Further, we construct a functor from a category of DSCs equipped with a certain subclass of morphisms to the opposite of the category of finite distributive lattices, making use of a simple finite characterization of the Bruns-Lakser completion.




- - - - Thursday, Oct 26, 2023 - - - -



- - - - Friday, Oct 27, 2023 - - - -

POSTPONED - Model Theory Seminar
Friday, Oct 27, 12:30-2:00pm NY time
David Marker, University of Illinois at Chicago
THIS TALK HAS BEEN POSTPONED TO A LATER DATE (TBD)


Logic Workshop
CUNY Graduate Center
Friday Oct 27, 2:00pm-3:30pm, Room 6417

Arnon Avron, Tel Aviv University
Poincaré-Weyl's predicativity: going beyond 

On the basis of Poincaré and Weyl's view of predicativity as invariance, we develop an extensive framework for predicative, type-free first-order set theory in which  and much bigger ordinals can be defined as von Neumann ordinals. This refutes the accepted view of  as the 'limit of predicativity.' We also explain what is wrong in Feferman-Schütte analysis of predicativity on which this view of  is based.




Next Week in Logic at CUNY:

- - - - Monday, Oct 30, 2023 - - - -

Rutgers Logic Seminar
Monday, Oct 30th, 3:30pm, Rutgers University, Hill 705
Paul Ellis, Rutgers

Logic and Metaphysics Workshop
Date: Monday, Oct 30, 4.15-6.15pm (NY time)
Room: Graduate Center Room 4419
Brad Armour-Garb (SUNY Albany).
Title: An approach to property-talk for property nominalists

Abstract: Properties, understood as immanent universals that are repeatable entities which distinct objects can each have at the same time and in different places, are weird, so weird, in fact, that if we could do without them, we probably should do so. An alternative to an approach that sanctions properties might suggest a deflationary view of property-talk according to which the raison d’être of our use of ‘property’ is that it serves a quasi-logical function that is akin to what alethic deflationists claim about truth-talk. Deflationists about property-talk normally subscribe to a form of property nominalism, which rejects the sort of property realism that takes properties to be immanent universals. In this talk, after highlighting some of the weirdness of, or worries for, property realism and explaining why certain forms of property nominalism should not be abided, I highlight the expressive role of property-talk and go on to explain how property-talk performs its roles by introducing what I call “adjectival predicate-variable deflationism” (“APVD”). As I will show, by incorporating APVD into a version of what I have called a “semantic-pretense involving fictionalism” (“SPIF”), we capture the full range of property-talk instances without compromising property nominalism. Time permitting, I will also highlight a virtue of my view, which another form of property nominalism cannot accommodate. If property nominalism is correct, then we should endorse the SPIF account of property-talk that I will develop in this talk.

Note: This is joint work with James A. Woodbridge.



- - - - Tuesday, Oct 31, 2023 - - - -



- - - - Wednesday, Nov 1, 2023 - - - -



- - - - Thursday, Nov 2, 2023 - - - -



- - - - Friday, Nov 3, 2023 - - - -

Model Theory Seminar
Friday, Nov 3, 12:30-2:00pm NY time, Room 5383 (modality TBA)
Alfred Dolich CUNY


Logic Workshop
CUNY Graduate Center
Friday Nov 3, 2:00pm-3:30pm, Room 6417
Karel Hrbacek, CUNY
Nonstandard methods without the Axiom of Choice

Model-theoretic frameworks for nonstandard methods entail the existence of nonprincipal ultrafilters over N, a strong version of the Axiom of Choice (AC). While AC is instrumental in many abstract areas of mathematics, such as general topology or functional analysis, its use in infinitesimal calculus or number theory should not be necessary.

Mikhail Katz and I have formulated a set theory SPOT in the language that has, in addition to membership, a unary predicate “is standard.” In addition to ZF, the theory has three simple axioms, Transfer, Nontriviality and Standard Part, that reflect the insights of Leibniz. It is a subtheory of the nonstandard set theories IST and HST, but unlike them, it is a conservative extension of ZF. Arguments carried out in SPOT thus do not depend on any form of AC. Infinitesimal calculus can be developed in SPOT as far as the global version of Peano's Theorem (the usual proofs of which use ADC, the Axiom of Dependent Choice). The existence of upper Banach densities can be proved in SPOT.

The conservativity of SPOT over ZF is established by a construction that combines the methods of forcing developed by Ali Enayat for second-order arithmetic and Mitchell Spector for set theory with large cardinals.

A stronger theory SCOT is a conservative extension of ZF+ADC. It is suitable for handling such features as an infinitesimal approach to the Lebesgue measure.

I will also formulate an extension of SPOT to a theory with multiple levels of standardness SPOTS, in which Renling Jin's recent groundbreaking proof of Szemeredi's Theorem can be carried out. While it is an open question whether SPOTS is conservative over ZF, SPOTS + DC (Dependent Choice for relations definable in it) is a conservative extension of ZF + ADC.

Reference: KH and M. G. Katz, Infinitesimal analysis without the Axiom of Choice, Ann. Pure Applied Logic 172, 6 (2021). https://doi.org/10.1016/j.apal.2021.102959, https://arxiv.org/abs/2009.04980 




- - - - Other Logic News - - - -

CONFERENCE ANNOUNCEMENT

The 2023 Category Theory Octoberfest will be held on the weekend of October 28th through October 29th. The meeting will be virtual. Following the tradition of past Octoberfests, this is intended to be an informal meeting, covering all areas of category theory and its applications.  Here is the official conference website:

 

https://richardblute.ca/octoberfest-2023/

 

At the moment, you'll find there the schedule with all speakers and titles, as well as the zoom link which will be the same for both days. The abstracts for all the talks will be available shortly.

 



- - - - Web Site - - - -

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

--------  ADMINISTRIVIA  --------

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

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

Logic Seminar Talks at NUS on 24 Oct, 31 Oct and 7 Nov 2023

NUS Logic Seminar
Invitations to the logic seminars in this and the next weeks. As Frank Stephan (who maintains this list) will be overseas, these invitations are sent jointly for 24 October, 31 October and 7 November 2023. Logic Seminar Tuesday 24/10/2023, 17:00 hrs, Room S17#04-06, Department of Mathematics, NUS. Speaker: Ho Meng-Che Title: Word problems of groups as ceers Abstract: Classically, the word problem of a group is the set of words equal to the identity of the group, and we analyze them using Turing reductions. In this talk, we consider the word problem of a group as a computably enumerable equivalence relation (ceer), namely, two words are equivalent if and only if they are equal in the group. We compare ceers using the computable reduction: E is reducible to F if there is a computable function f so that i E j if and only if f(i) F f(j). We will discuss some recent results and see that the landscape of word problems as ceers is very different from the classical theory. For instance, in the classical setting, any Turing degree can be realized as a word problem by first constructing a countable group and then embedding it into a finitely presented group via the Higman embedding theorem. However, we prove that in the ceer setting, there is a group G whose word problem is not universal, but for any nontrivial H, the free product of G and H has a universal word problem. This is a joint work with Uri Andrews and Luca San Mauro. Logic Seminar Tuesday 31/10/2023, 17:00 hrs, Room S17#04-06, Department of Mathematics, NUS. Speaker: Samuel Alfaro Tanuwijaya Title: Generalisations of the Posner Robinson theorem Abstract: The talk will deal with relativised versions of the Posner Robinson theorem and explore how far one can go and how to prove these relatived versions. Logic Seminar Tuesday 07/11/2023, 17:00 hrs, Room S17#04-06, Department of Mathematics, NUS. Speakier: Liu Shixiao Title: Density forcings that collapse the continuum Abstract: Last semester I talked about the upper density Mathias forcing which we prove to be proper. This time we take a look at several similar forcings, each of which collapses the continuum to omega and thus fails to be proper.

(KGRC) talk in the Model Theory Seminar on Wednesday, October 25

Kurt Godel Research Center
Model Theory Seminar Kurt Gödel Research Center Wednesday, October 25 "On Whitney's extension problem in o-minimal structures" Armin Rainer (Universität Wien) In 1934, Whitney raised the question of how one can decide whether a function $f$ defined on a closed subset $X$ of $\mathbb R^n$ is the restriction of a $C^m$ function on $\mathbb R^n$. He gave a characterization in dimension $n=1$. The problem was fully solved by Fefferman in 2006. In this talk, I will discuss a related conjecture: if a semialgebraic function $f : X \to \mathbb R$ has a $C^m$ extension to $\mathbb R^n$, then it has a semialgebraic $C^m$ extension. In particular, I will show that the $C^{1,\omega}$ case of the conjecture is true, even in o-minimal expansions of the real field, where $\omega$ is a definable modulus of continuity. The proof is based on definable Lipschitz selections for affine-set valued maps. This is joint work with Adam Parusinski. Time and Place Talk at 11:30am on-site Universität Wien Institut für Mathematik Kolingasse 14-16 1090 Wien 1st floor Seminar room 10 Please direct any questions about this talk to matthias.aschenbrenner@univie.ac.at.

Set Theory and Topology Seminar 24.10.2023 Maciej Korpalski

Wrocław Set Theory Seminar
I am happy to announce that at the seminar in Set Theory and Topology on Tuesday 24.10.2023 at 17:15 in room 601 (Mathematical Institute, University of Wrocław) the lecture:
"Straightening almost chains into barely altenating ones"

will be presented by

Maciej Korpalski


Abstract.

Consider an almost chain $\mathcal{A} = \{A_x \subset \omega: x \in X\}$ for some separable linearly ordered set $X$. Such a chain is barely alternating if for all $n \in \omega$ we cannot find elements $x_1 < x_2 < x_3 < x_4$ in $X$ satisfying $n \in A_{x_1}, A_{x_3}$, $n \notin A_{x_2}, A_{x_4}$. We will show that under $MA(\kappa)$, if $|X| \leq \kappa$, then we can straighten our almost chain $\mathcal{A}$ into a barely alternating one by changing at most finitely many elements in each set $A_x$.


Feel free to spread this information among Your colleagues.

I'm looking forward to seeing You
Szymon Żeberski

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

About 15 minutes before the seminar we invite you for coffee and a chat to social room.


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

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

(KGRC) seminar talks Wednesday, October 18, and Thursday, October 19

Kurt Godel Research Center
The KGRC welcomes as guests: Corey Switzer visits the KGRC until December 31. David Asperó visits the KGRC from December 11 until December 15 and gives a talk, details to be announced at a later time. * * * Model Theory & Set Theory Seminar Kurt Gödel Research Center Wednesday, October 18 "The Local Lemma in descriptive combinatorics: a survey and recent developments" Anton Bernshteyn (Georgia Institute of Technology, Atlanta, US) The Lovász Local Lemma is a classical tool in probabilistic combinatorics with numerous and diverse applications. In this talk, I will survey what is known about the behavior of the Local Lemma in the Borel and measurable context, including some very recent progress, and state several open problems. Parts of this talk are based on joint work with Jing Yu and Felix Weilacher. Time and Place Talk at 10:30am in hybrid mode: on-site as well as via Zoom Universität Wien Institut für Mathematik Kolingasse 14-16 1090 Wien 1st floor Seminar room 10 Zoom: If you have not received the Zoom data, please contact richard.springer@univie.ac.at. Please direct any other questions about this talk to vera.fischer@univie.ac.at. * * * Logic Colloquium Kurt Gödel Research Center Thursday, October 19 "Spectra of Computable Models of Strongly Minimal Disintegrated Theories in Rank 1 Languages" Steffen Lempp (University of Wisconsin, Madison, US) In this talk, we study, for a given first-order theory T, which countable models of T can be presented effectively. We consider this question for a particular class of theories, the so-called strongly minimal disintegrated theories, where the countable models can be characterized by their dimension. The spectrum of computable models of T is the subset S of $\omega+1$ such that $\alpha$ is in S if and only if the $\alpha$-th model of T can be effectively presented. We examine the class of strongly minimal disintegrated theories in computable relational languages where each relation symbol defines a set of Morley rank at most 1. We characterize the spectra of computable models of such theories (exactly, with the exception of three sets) under the assumption of bounded arity on the language, and (with the exception of three sets and one specific class of sets) without that assumption. We also determine the exactly seven possible spectra for strongly minimal theories in binary relational languages and show that there are at least nine but no more than eighteen spectra of disintegrated theories in ternary relational languages. Time and Place Talk at 3:00pm in hybrid mode: on-site as well as via Zoom Universität Wien Institut für Mathematik Oskar-Morgenstern-Platz 1 1090 Wien 2nd floor room HS 11 Zoom: If you have not received the Zoom data, please contact richard.springer@univie.ac.at. Please direct any other questions about this talk to vera.fischer@univie.ac.at.

This Week in Logic at CUNY

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

- - - - Monday, Oct 16, 2023 - - - -

Rutgers Logic Seminar
Monday, Oct 16th, 3:30pm, Rutgers University, Hill 705
Justin Moore, Cornell
Large minimal non-σ-scattered linear orders



Logic and Metaphysics Workshop
Date: Monday, Oct 16, 4.15-6.15pm (NY time)
Room: Graduate Center Room 4419
Yale Weiss (CUNY)
Title: Maximal deontic logic

Abstract: The worlds accessible from a given world in Kripke models for deontic logic are often informally glossed as ideal or perfect worlds (at least, relative to the base world). Taking that language seriously, a straightforward but nonstandard semantic implementation using models containing maximally good worlds yields a deontic logic, MD, considerably stronger than that which most logicians would advocate for. In this talk, I examine this logic, its philosophical significance, and its technical properties, as well as those of the logics in its vicinity. The principal technical result is a proof that MD is pretabular (it has no finite characteristic matrix but all of its proper normal extensions do). Along the way, I also characterize all normal extensions of the quirky deontic logic D4H, prove that they are all decidable, and show that D4H has exactly two pretabular normal extensions.



- - - - Tuesday, Oct 17, 2023 - - - -

Models of Peano Arithmetic (MOPA)
Tuesday, Oct 17, 1:00pm
Virtual (email Victoria Gitman vgitman@gmail.com for meeting id)

Elliot Glazer, Harvard University
Coin flipping on models of arithmetic to define the standard cut

We will discuss the following claim: 'The standard cut of a model  of PA (or even Q) is uniformly definable with respect to a randomly chosen predicate.' Restricting our consideration to countable models, this claim is true in the usual sense, i.e. there is a formula  such that for any countable model of arithmetic  the set  is Lebesgue measure 1. However, if  is countably saturated, then there is no  such that  is measured by the completed product measure on  We will identify various combinatorial ideals on  that can be used to formalize the original claim with no restriction on the cardinality of  and discuss the relationship between closure properties of these ideals and principles of choice.




- - - - Wednesday, Oct 18, 2023 - - - -

The New York City Category Theory Seminar
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York
URL:  http://www.sci.brooklyn.cuny.edu/~noson/Seminar/index.html

Speaker:     Michael Shulman, University of San Diego.

Date and Time:     Wednesday October 18, 2023, 7:00 - 8:30 PM.  ZOOM TALK

Title:     The derivator of setoids.


Abstract: The question of "what is a homotopy theory" or "what is a higher category" is already interesting in classical mathematics, but in constructive mathematics (such as the internal logic of a topos) it becomes even more subtle. In particular, existing constructive attempts to formulate a homotopy theory of spaces (infinity-groupoids) have the curious property that their "0-truncated objects" are more general than ordinary sets, being instead some kind of "free exact completion" of the category of sets (a.k.a. "setoids"). It is at present unclear whether this is a necessary feature of a constructive homotopy theory or whether it can be avoided somehow. One way to find some evidence about this question is to use the "derivators" of Heller, Franke, and Grothendieck, as they give us access to higher homotopical structure without depending on a preconcieved notion of what such a thing should be. It turns out that constructively, the free exact completion of the category of sets naturally forms a derivator that has a universal property analogous to the classical category of sets and to the classical homotopy theory of spaces: it is the "free cocompletion of a point" in a certain universe. This suggests that either setoids are an unavoidable aspect of constructive homotopy theory, or more radical modifications to the notion of homotopy theory are needed.



- - - - Thursday, Oct 19, 2023 - - - -



- - - - Friday, Oct 20, 2023 - - - -

Logic Workshop
CUNY Graduate Center
Friday Oct 20, 2:00pm-3:30pm, Room 6417
Rehana Patel, Wesleyan University

The number of ergodic models of an infinitary sentence

Given an -sentence  in a countable language, we call an ergodic -invariant probability measure on the Borel space of countable models of  (having fixed underlying set) an ergodic model of . I will discuss the number of ergodic models of such a sentence , including the case when  is a Scott sentence. This is joint work with N. Ackerman, C. Freer, A. Kruckman and A. Kwiatkowska.





Next Week in Logic at CUNY:

- - - - Monday, Oct 23, 2023 - - - -

Rutgers Logic Seminar
Monday, Oct 23rd, 3:30pm, Rutgers University, Hill 705
Forte Shinko, Berkeley


Logic and Metaphysics Workshop
Date: Monday, Oct 23, 4.15-6.15pm (NY time)
Room: Graduate Center Room 4419

Melissa Fusco (Columbia)
Title: Diachronic reasoning with conditionals

Abstract: I will discuss a hybrid decision theory, coinciding sometimes with (traditional) Evidential Decision Theory, but usually with (traditional) Causal Decision Theory, which is inspired by recent work on unified and fully compositional approaches to the probabilities of conditionals. The hybrid theory features a few other loci of interest: the partitionality of acts A ∈ {A} fails, and close attention is paid to how one might (dis)confirm chance hypotheses under the umbrella of the Principal Principle. On this theory, the probabilities of conditionals play a role in underwriting a theory of imaging that follows Skyrms’s Thesis (Skyrms, 1981, 1984). Moreover, the credences it is epistemically rational to assign to these conditionals guides updating on one’s own acts. This implies some departures from Conditionalization, which I defend on epistemological grounds.




- - - - Tuesday, Oct 24, 2023 - - - -

Models of Peano Arithmetic (MOPA)
Tuesday, Oct 24, 1:00pm
Virtual (email Victoria Gitman vgitman@gmail.com for meeting id)

Alessandro Berarducci and Marcello Mamino, University of Pisa
Provability logic: models within models in Peano Arithmetic

In 1994 Jech gave a model theoretic proof of Gödel's second incompleteness theorem for Zermelo-Fraenkel set theory in the following form: ZF does not prove that ZF has a model. Kotlarski showed that Jech's proof can be adapted to Peano Arithmetic with the role of models being taken by complete consistent extensions. In this note we take another step in the direction of replacing proof-theoretic by model-theoretic arguments. We show, without passing through the arithmetized completeness theorem, that the existence of a model of PA of complexity  is independent of PA, where a model is identified with the set of formulas with parameters which hold in the model. Our approach is based on a new interpretation of the provability logic of Peano Arithmetic with the modal operator interpreted as truth in every -model.



- - - - Wednesday, Oct 25, 2023 - - - -

The New York City Category Theory Seminar
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York
URL:  http://www.sci.brooklyn.cuny.edu/~noson/Seminar/index.html

Speaker:     Emilio Minichiello, CUNY Graduate Center.

Date and Time:     Wednesday October 25, 2023, 7:00 - 8:30 PM. IN PERSON TALK (GC 6417)

Title:     A Mathematical Model of Package Management Systems.


Abstract: In this talk, I will review some recent joint work with Gershom Bazerman and Raymond Puzio. The motivation is simple: provide a mathematical model of package management systems, such as the Hackage package respository for Haskell, or Homebrew for Mac users. We introduce Dependency Structures with Choice (DSC) which are sets equipped with a collection of possible dependency sets for every element and satisfying some simple conditions motivated from real life use cases. We define a notion of morphism of DSCs, and prove that the resulting category of DSCs is equivalent to the category of antimatroids, which are mathematical structures found in combinatorics and computer science. We analyze this category, proving that it is finitely complete, has coproducts and an initial object, but does not have all coequalizers. Further, we construct a functor from a category of DSCs equipped with a certain subclass of morphisms to the opposite of the category of finite distributive lattices, making use of a simple finite characterization of the Bruns-Lakser completion.




- - - - Thursday, Oct 26, 2023 - - - -



- - - - Friday, Oct 27, 2023 - - - -

Model Theory Seminar
Friday, Oct 27, 12:30-2:00pm NY time, GC Room 5383
Hybrid: Please email Victoria Gitman (vgitman@gmail.com) for meeting id.
David Marker, University of Illinois at Chicago



Logic Workshop
CUNY Graduate Center
Friday Oct 27, 2:00pm-3:30pm, Room 6417

Arnon Avron, Tel Aviv University
Poincaré-Weyl's predicativity: going beyond 

On the basis of Poincaré and Weyl's view of predicativity as invariance, we develop an extensive framework for predicative, type-free first-order set theory in which  and much bigger ordinals can be defined as von Neumann ordinals. This refutes the accepted view of  as the 'limit of predicativity.' We also explain what is wrong in Feferman-Schütte analysis of predicativity on which this view of  is based.



- - - - Other Logic News - - - -

CONFERENCE ANNOUNCEMENT
NERDS 24.0 (New England Recursion and Definability Seminar)
Date: October 14, 2023
Place: Wellesley College – All talks in Science Center N321
Speakers:
Caleb Camrud (Brown University)
Gihanee Senadheera (Winthrop College)
Alex van Abel (Wesleyan University)
Neil Lutz (Swarthmore College)



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

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

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

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


- - - - Web Site - - - -

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

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Set Theory and Topology Seminar 17.10.2023 Viktoriia Brydun

Wrocław Set Theory Seminar
I am happy to announce that at the seminar in Set Theory and Topology on Tuesday 17.10.2023 at 17:15 in room 603 (Mathematical Institute, University of Wrocław) the lecture:
"Monad on FMS(•) (Fuzzy Metric Spaces Category)"

will be presented by

Viktoriia Brydun (Ivan Franko Lviv National University)


Feel free to spread this information among Your colleagues.

I'm looking forward to seeing You
Szymon Żeberski

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

About 15 minutes before the seminar we invite you for coffee and a chat to social room.


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

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

Logic Seminar 17 Oct 2023 17:00 hrs by Frank Stephan at NUS Mathematics

NUS Logic Seminar
Invitation to the Logic Seminar at the National University of Singapore Date: Tuesday, 17 October 2023, 17:00 hrs Place: NUS, Department of Mathematics, S17#04-06 Speaker: Frank Stephan, National University of Singapore Co-Authors: Sanjay Jain, Xiaodong Jia and Ammar Fathin Sabili Title: Addition Machines, Automatic Functions and the Open Problems of Floyd and Knuth Abstract: Floyd and Knuth studied in their 1990 paper addition machines which are machines which can add, subtract and compare integers (<,=,>) in unit time; also the reading or writing of an integer is in unit time. They showed that multiplying and dividing can be done in linear time with six registers and asked in their Open Problem (2) whether this bound can be broken; furthermore, they asked in Open Problem (5) of their paper whether there is a register machine which can output in subquadratic time the powers of two occurring in the binary representation of an integer. The talk answers both questions affirmatively and presents the key ideas and programs to witness this. The slides for the joint paper on addition machines are on https://www.comp.nus.edu.sg/~fstephan/logicseminar.html#weeknine A technical report version of the paper is on https://arxiv.org/abs/2111.08969 The paper appeared in the Journal of Computer and System Sciences volume 136, pages 135-156, 2023 under the title "Addition machines, automatic functions and open problems of Floyd and Knuth". The original paper of Floyd and Knuth appeared in the SIAM Journal on Computing, 19(2), 329-340, 1990 and is available as a technical report on http://infolab.stanford.edu/pub/cstr/reports/cs/tr/89/1268/CS-TR-89-1268.pdf as a scanned version of the report. URL: http://www.comp.nus.edu.sg/~fstephan/logicseminar.html

(KGRC) talks Wednesday (TODAY), Thursday, and Friday

Kurt Godel Research Center
The KGRC welcomes as guests: Corey Switzer visits the KGRC until December 31. Roman Kossak visits the KGRC until October 13 and gives a talk (see below). Šárka Stejskalová visits the KGRC until October 15 and gives a talk (see below). Radek Honzík visits the KGRC until October 15 and gives a talk (see below). David Asperó visits the KGRC from December 11 until December 15 and gives a talk, details to be announced at a later time. * * * For a video recording of the first part of Damian Sobota's mini-course, please use https://univienna.zoom.us/rec/share/Q6jN04EmLJVbrEeRBQOkSEHIb3JTcVBCvk5K0974htqthimM5O6UnAHoG6fPgw_N.DPdwRWd4hdgSNpej?startTime=1696498409000 and pass code PG4hg%kX * * * Model Theory Seminar Kurt Gödel Research Center Wednesday, October 11 (TODAY) "Surreal numbers in homotopy type theory" David Raffelsberger (Uni Wien) Since their inception in the 1970s, various constructions of the surreal numbers have been discovered. In the classical setting, they were defined as a special class of so-called Games. They were also constructed as expansions of {−, +} of ordinal length. As another example, J. Conway constructed a field isomorphism between the surreals and the field of Hahn Series with real coefficients on the value group of the surreals. This talk will present a more recent construction, first done in the HoTT book, defining the surreals as a higher-inductive type. The talk is intended for an audience that is not yet familiar with homotopy type theory. Thus, the main part of the talk will be spent introducing the basic concepts of homotopy type theory with the two aims of formalizing first-order logic inside homotopy type theory and defining the surreals as a higher-inductive type. In the last part, we will look at a consequence of the constructive nature of homotopy type theory, namely that the surreals defined this way fail to be (weakly) totally ordered. Time and Place Talk at 11:30am on-site Universität Wien Institut für Mathematik Kolingasse 14-16 1090 Wien 1st floor Seminar room 10 Please direct any questions about this talk to matthias.aschenbrenner@univie.ac.at. * * * Set Theory Seminar Kurt Gödel Research Center Thursday, October 12 "Convergence in Banach spaces of measures and cardinal characteristics of the continuum, II" Damian Sobota (KGRC) Mini-course (05.10.2023-23.11.2023, 6 lectures) - 2nd lecture: During the second lecture we will briefly discuss the notion of weak topologies on Banach spaces, after which we state two important theorems concerning convergence of sequences of measures on Boolean algebras: the Grothendieck theorem and Nikodym's Uniform Boundedness Theorem. If time permits, we will prove the latter result. Time and Place Talk at 11:30am in hybrid mode: on-site as well as via Zoom Universität Wien Institut für Mathematik Kolingasse 14-16 1090 Wien 1st floor Seminar room 10 Zoom: If you have not received the Zoom data, please contact richard.springer@univie.ac.at. Please direct any other questions about this talk to vera.fischer@univie.ac.at. * * * Logic Colloquium Kurt Gödel Research Center Thursday, October 12 "Undefinability and Absolute Undefinability" Roman Kossak (City University of New York, US) I call a subset of the domain of a countable model absolutely undefinable if the set of its images under automorphisms of the model is uncountable. By the Kueker-Reyes theorem, all sets that are not absolutely undefinable are parametrically definable in $L_{\omega_1 \omega}$. I will survey classical results about first-order undefinability in the standard model of arithmetic, and I will contrast them with some old and some new results about absolute undefinability in nonstandard models of PA. Time and Place Talk at 3:00pm in hybrid mode: on-site as well as via Zoom Universität Wien Institut für Mathematik Oskar-Morgenstern-Platz 1 1090 Wien 2nd floor room HS 11 Zoom: If you have not received the Zoom data, please contact richard.springer@univie.ac.at. Please direct any other questions about this talk to vera.fischer@univie.ac.at. * * * Set Theory Seminar Kurt Gödel Research Center Thursday, October 12 "The tower number and the ultrafilter number on an inaccessible cardinal $\kappa$ with compactness at $\kappa^{++}$" Radek Honzík (Charles University, Prague, CZ) We will use a construction due to Brooke-Taylor, Fischer, Friedman, and Montoya and construct a model where $\kappa$ is inaccessible and we have (among other things) $\kappa^+ = \mathfrak{t}(\kappa) < \mathfrak{u}(\kappa) < 2^\kappa$, and the tree property, and the negation of the weak Kurepa Hypothesis hold at $\kappa^{++}$. This is an application of a general method based on indestructibility of various compactness principles by further forcings. The consistency of $\kappa^+ < \mathfrak{t}(\kappa) \leq \mathfrak{u}(\kappa) < 2^\kappa$ with the same compactness principles remains open because it is not solved by the present technique. Time and Place Talk at 4:45pm in hybrid mode: on-site as well as via Zoom Universität Wien Institut für Mathematik Kolingasse 14-16 1090 Wien 1st floor Seminar room 10 Zoom: If you have not received the Zoom data, please contact richard.springer@univie.ac.at. Please direct any other questions about this talk to vera.fischer@univie.ac.at. * * * Set Theory Seminar Kurt Gödel Research Center Thursday, October 12 "Automorphisms of trees" Šárka Stejskalová (Charles University, Prague, CZ) In the talk we will focus on automorphisms of $\omega_1$-trees. We will discuss how to add an automorphism to an $\omega_1$-tree with a well-behaved forcing, and we will identify some restrictions for these forcings (for instance, they cannot be $\sigma$-closed for Suslin trees). In the last part of the talk, we will mention some open questions regarding automorphisms of $\omega_1$-trees. Time and Place Talk at 5:30pm in hybrid mode: on-site as well as via Zoom Universität Wien Institut für Mathematik Kolingasse 14-16 1090 Wien 1st floor Seminar room 10 Zoom: If you have not received the Zoom data, please contact richard.springer@univie.ac.at. Please direct any other questions about this talk to vera.fischer@univie.ac.at. * * * Set Theory Seminar Kurt Gödel Research Center Friday, October 13 "Peculiar maximal eventually different families" Lukas Schembecker (KGRC) In my talk I will discuss a new notion of strong maximality for maximal eventually different families and explore some applications for the corresponding cardinal characteristic $\mathfrak{a}_e$ and its spectrum. Time and Place Talk at 9:45am in hybrid mode: on-site as well as via Zoom Universität Wien Institut für Mathematik Kolingasse 14-16 1090 Wien 1st floor Seminar room 10 Zoom: If you have not received the Zoom data, please contact richard.springer@univie.ac.at. Please direct any other questions about this talk to vera.fischer@univie.ac.at. * * * Set Theory Seminar Kurt Gödel Research Center Friday, October 13 "Splitting and bounding at the uncountable" Vera Fischer (KGRC) We will discuss some new constellations regards the splitting, bounding and reaping numbers at the uncountable and outline the consistency of $\kappa^+ < \mathfrak{s}(\kappa) < \mathfrak{b}(\kappa) = \mathfrak{d}(\kappa) < \mathfrak{r}(\kappa) = 2^\kappa$, for $\kappa$ supercompact. This is a joint work with Diego Mejia. Time and Place Talk at 10:30am in hybrid mode: on-site as well as via Zoom Universität Wien Institut für Mathematik Kolingasse 14-16 1090 Wien 1st floor Seminar room 10 Zoom: If you have not received the Zoom data, please contact richard.springer@univie.ac.at. Please direct any other questions about this talk to vera.fischer@univie.ac.at.

This Week in Logic at CUNY

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

- - - - Monday, Oct 9, 2023 - - - -

CUNY Graduate Center CLOSED TODAY


- - - - Tuesday, Oct 10, 2023 - - - -



- - - - Wednesday, Oct 11, 2023 - - - -

The New York City Category Theory Seminar
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York
URL:  http://www.sci.brooklyn.cuny.edu/~noson/Seminar/index.html

Speaker:     Thiago Alexandre, University of São Paulo (Brazil).

Date and Time:     Wednesday October 11, 2023, 7:00 - 8:30 PM.

Title:     Internal homotopy theories.


Abstract: The idea of 'Homotopy theories' was introduced by Heller in his seminal paper from 1988. Two years later, Grothendieck discovered the theory of derivators (1990), exposed in his late manuscript Les Dérivateurs, and developed further by several authors. Essentially, there are no significant differences between Heller's homotopy theories and Grothendieck's derivators. They are tautologically the same 2-categorical yoga. However, they come from distinct motivations. For Heller, derivators should be a definitive answer to the question "What is a homotopy theory?", while for Grothendieck, who was strongly inspired by topos cohomology, the first main motivation for derivators was to surpass some technical deficiencies that appeared in the theory of triangulated categories. Indeed, Grothendieck designed the axioms of derivators in light of a certain 2-functorial construction, which associates the corresponding (abelian) derived category to each topos, and more importantly, inverse and direct cohomological images to each geometric morphism. It was from this 2-functorial construction, from where topos cohomology arises, that Grothendieck discovered the axioms of derivators, which are surprisingly the same as Heller's homotopy theories. Nowadays, it is commonly accepted that a homotopy theory is a quasi-category, and they can all be presented by a localizer (M,W), i.e., a couple composed by a category M and a class of arrows in W. This point of view is not so far from Heller, since pre-derivators, quasi-categories, and localizers, are essentially equivalent as an answer to the question "What is a homotopy theory?". In my talk, I will expose these subjects in more detail, and I am also going to explore how to internalize a homotopy theory in an arbitrary (Grothendieck) topos, a problem which strongly relates formal logic and homotopical algebra.



- - - - Thursday, Oct 12, 2023 - - - -



- - - - Friday, Oct 13, 2023 - - - -

Model Theory Seminar
Friday, Oct 13, 12:30-2:00pm NY time, GC Room 5383
Hybrid: Please email Victoria Gitman (vgitman@gmail.com) for meeting id.
Vincent Guingona Towson University

Vincent Guingona, Towson University
Indivisibility of Classes of Graphs

This talk will discuss my work with Miriam Parnes and four undergraduates which took place last summer at an REU at Towson University. We say that a class of structures in some fixed language is indivisible if, for all structures A in the class and number of colors k, there is a structure B in the class such that, no matter how we color B with k colors, there is a monochromatic copy of A in B. Parnes and I became interested in this property when studying the classification of theories via positive combinatorial configurations. In this talk, following the work with our students, I will examine indivisibility on classes of graphs. In particular, we will look at hereditarily sparse graphs, cographs, perfect graphs, threshold graphs, and a few other classes. This work is joint with Felix Nusbaum, Zain Padamsee, Miriam Parnes, Christian Pippin, and Ava Zinman.





Logic Workshop
CUNY Graduate Center
Friday Oct 13, 2:00pm-3:30pm, Room 6417

Philipp Rothmaler, CUNY
A theorem of Makkai implying the existence of strict Mittag-Leffler modules in a definable subcategory

In 1982 Makkai published a very general theorem about the existence of what he later called principally prime (we call them positive atomic) models of so-called regular theories [FULL CONTINUOUS EMBEDDINGS OF TOPOSES, TAMS 269], which seems to have gone largely unnoticed. (Regular he called those theories that are axiomatized by positive primitive (=pp) implications.) This is a strong existence result in some sort of positive logic in a very general categorical (including non-additive) setting. I first discuss its significance for definable subcategories of modules (=model categories of regular theories of modules), which play an important role in representation theory and module theory in general. Part of this is that there these models are precisely the strict Mittag-Leffler modules contained in and relativized to such definable subcategories. Makkai’s original proof is, in its generality, not easy to follow, and so it is of interest, especially to the algebraic community, to find an easier proof for modules. I present a recent one due to Prest. At the time being it works only for countable rings, in the uncountable case one still has to rely on Makkai’s original proof.



- - - - Saturday, Oct 14, 2023 - - - -

NERDS 24.0
New England Recursion and Definability Seminar
Date: October 14, 2023
Place: Wellesley College – All talks in Science Center N321



Next Week in Logic at CUNY:

- - - - Monday, Oct 16, 2023 - - - -

Rutgers Logic Seminar
Monday, Oct 16th, 3:30pm, Rutgers University, Hill 705
Justin Moore, Cornell
Large minimal non-σ-scattered linear orders



Logic and Metaphysics Workshop
Date: Monday, Oct 16, 4.15-6.15pm (NY time)
Room: Graduate Center Room 4419
Yale Weiss (CUNY)
Title: Maximal deontic logic

Abstract: The worlds accessible from a given world in Kripke models for deontic logic are often informally glossed as ideal or perfect worlds (at least, relative to the base world). Taking that language seriously, a straightforward but nonstandard semantic implementation using models containing maximally good worlds yields a deontic logic, MD, considerably stronger than that which most logicians would advocate for. In this talk, I examine this logic, its philosophical significance, and its technical properties, as well as those of the logics in its vicinity. The principal technical result is a proof that MD is pretabular (it has no finite characteristic matrix but all of its proper normal extensions do). Along the way, I also characterize all normal extensions of the quirky deontic logic D4H, prove that they are all decidable, and show that D4H has exactly two pretabular normal extensions.



- - - - Tuesday, Oct 17, 2023 - - - -

Models of Peano Arithmetic (MOPA)
Tuesday, Oct 17, 1:00pm
Virtual (email Victoria Gitman vgitman@gmail.com for meeting id)

Elliot Glazer, Harvard University
Coin flipping on models of arithmetic to define the standard cut

We will discuss the following claim: 'The standard cut of a model  of PA (or even Q) is uniformly definable with respect to a randomly chosen predicate.' Restricting our consideration to countable models, this claim is true in the usual sense, i.e. there is a formula  such that for any countable model of arithmetic  the set  is Lebesgue measure 1. However, if  is countably saturated, then there is no  such that  is measured by the completed product measure on  We will identify various combinatorial ideals on  that can be used to formalize the original claim with no restriction on the cardinality of  and discuss the relationship between closure properties of these ideals and principles of choice.




- - - - Wednesday, Oct 18, 2023 - - - -

The New York City Category Theory Seminar
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York
URL:  http://www.sci.brooklyn.cuny.edu/~noson/Seminar/index.html

Speaker:     Michael Shulman, University of San Diego.

Date and Time:     Wednesday October 18, 2023, 7:00 - 8:30 PM.

Title:     The derivator of setoids.




- - - - Thursday, Oct 19, 2023 - - - -



- - - - Friday, Oct 20, 2023 - - - -

Logic Workshop
CUNY Graduate Center
Friday Oct 20, 2:00pm-3:30pm, Room 6417
Rehana Patel, Wesleyan University


- - - - Other Logic News - - - -

CONFERENCE ANNOUNCEMENT
NERDS 24.0 (New England Recursion and Definability Seminar)
Date: October 14, 2023
Place: Wellesley College – All talks in Science Center N321
Speakers:
Caleb Camrud (Brown University)
Gihanee Senadheera (Winthrop College)
Alex van Abel (Wesleyan University)
Neil Lutz (Swarthmore College)



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

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

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

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


- - - - Web Site - - - -

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

--------  ADMINISTRIVIA  --------

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

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

Wednesday seminar

Prague Set Theory Seminar
Dear all, There will be no seminar on Wednesday October 11th. Very likely, no seminar on Wednesday October 18th either. John Krueger will be visiting Prague during the week of October 16--20 (however, at there are no plans for him to give any seminar talks, afaik). https://www.math.unt.edu/~jkrueger/ People are encouraged to get in touch with John in case they are interested in interaction. Best, David

Set Theory and Topology Seminar 10.10.2023 Arturo Martinez

Wrocław Set Theory Seminar
I am happy to announce that at the seminar in Set Theory and Topology on Tuesday 10.10.2023 at 17:15 in room 603 (Mathematical Institute, University of Wrocław) the lecture:
"Cardinal invariants related to free sets"

will be presented by

Arturo Martinez


Feel free to spread this information among Your colleagues.

I'm looking forward to seeing You
Szymon Żeberski

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

Abstract:

(Joint work with T. Żuchowski) Given a function f without fixed points, an infinite set A is called free for f if f[A] \cap A = \emptyset. In this talk we will discuss some cardinal invariants related to families of free sets and we will discuss their relation between some cardinal invariants related to category and measure.

About 15 minutes before the seminar we invite you for coffee and a chat to social room.


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

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

This Week in Logic at CUNY

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

- - - - Monday, Oct 2, 2023 - - - -

Rutgers Logic Seminar
Monday, Oct 2nd, 3:30pm, Rutgers University, Hill 705
Philip Stetson, Rutgers
Characterizing LEF groups

Philip Stetson (Rutgers) will speak about Characterizing LEF groups.

Abstract: We propose a concrete characterization of locally-embeddable-into-finite (LEF) groups of cardinality larger than the continuum in terms of embeddings into the reduced product of finite symmetric groups. We show that whether this characterization holds is independent of ZFC. Analogous work has been done for the more general class of sofic groups. This is joint work with Simon Thomas.



Logic and Metaphysics Workshop
Date: Monday, Oct 2, 4.15-6.15pm (NY time)
Room: Graduate Center Room 4419
For meeting information, please sign up for our mailing list at https://logic.commons.gc.cuny.edu/about/
Brett Topey (Salzburg)
Title: Whence admissibility constraints? From inferentialism to tolerance

Abstract: Prior’s invented connective ‘tonk’ is sometimes taken to reveal a problem for certain inferentialist approaches to metasemantics: according to such approaches, the truth-theoretic features of our expressions are fully determined by the rules of inference we’re disposed to follow, but admitting the ‘tonk’ rules into a language would lead to intuitively absurd results. Inferentialists tend to insist that they can avoid these results: there are constraints on what sets of inference rules can be admitted into a language, the story goes, and the rules governing disruptive expressions like ‘tonk’ are defective and so illegitimate. I argue, though, that from an inferentialist perspective, there’s no genuine sense in which rules like the ‘tonk’ rules are defective; those who endorse the relevant sort of inferentialism turn out to be committed to Carnap’s principle of tolerance. I then sketch an argument to the effect that this, despite appearances, isn’t a problem for inferentialism.



- - - - Tuesday, Oct 3, 2023 - - - -



- - - - Wednesday, Oct 4, 2023 - - - -



- - - - Thursday, Oct 5, 2023 - - - -



- - - - Friday, Oct 6, 2023 - - - -

Logic Workshop
CUNY Graduate Center
Friday Sept 29, 2:00pm-3:30pm, Room 6417

Jenna Zomback, University of Maryland
Ergodic theorems along trees

In the classical pointwise ergodic theorem for a probability measure preserving (pmp) transformation , one takes averages of a given integrable function over the intervals  in front of the point . We prove a “backward” ergodic theorem for a countable-to-one pmp , where the averages are taken over subtrees of the graph of  that are rooted at  and lie behind  (in the direction of ). Surprisingly, this theorem yields forward ergodic theorems for countable groups, in particular, one for pmp actions of free groups of finite rank, and can be extended to yield ergodic theorems for pmp actions of free semigroups as well. In each case, the averages are taken along subtrees of the standard Cayley graph rooted at the identity. This is joint work with Anush Tserunyan.





Next Week in Logic at CUNY:

- - - - Monday, Oct 9, 2023 - - - -



- - - - Tuesday, Oct 10, 2023 - - - -



- - - - Wednesday, Oct 11, 2023 - - - -

The New York City Category Theory Seminar
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York
URL:  http://www.sci.brooklyn.cuny.edu/~noson/Seminar/index.html
Speaker:     Thiago Alexandre,
Date and Time:     Wednesday October 11, 2023, 7:00 - 8:30 PM.
Title:     ...derivator.... 


- - - - Thursday, Oct 12, 2023 - - - -



- - - - Friday, Oct 13, 2023 - - - -

Model Theory Seminar
Friday, Oct 13, 12:30-2:00pm NY time, GC Room 5383
Hybrid: Please email Victoria Gitman (vgitman@gmail.com) for meeting id.
Vincent Guingona Towson University




- - - - Other Logic News - - - -

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

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

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

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


- - - - Web Site - - - -

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

--------  ADMINISTRIVIA  --------

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

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

Wednesday seminar

Prague Set Theory Seminar
Dear all, The seminar meets on Wednesday October 4th at 11:00 in the Institute of Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building. Program: Peter Vojtáš -- Infinitary Ramsey theorem RT^3_2 is (strictly?) stronger than Bolzano–Weierstrass theorem? Reverse mathematics offers tools to compare strength of\forall\exists theorems around continuum (considering them in weak PA2). We review some old results on simple cardinal characteristics of continuum (mainly from A. Blass) and reformulate them in Galois–Tukey reductions. Some new observations and problems arose. In our March talk we considered problems with finite instances and various complements – here everything is infinite. Best, David

Update - Logic Workshop cancelled today: This Week in Logic at CUNY

This Week in Logic at CUNY

Hi everyone,

Today's talk by James Walsh in the Logic Workshop is cancelled due to flooding and subway outages.  Everyone be careful out there,

Jonas 



This Week in Logic at CUNY:

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

NO CLASSES AT CUNY TODAY

Rutgers Logic Seminar
Monday, Sept 25th, 3:30pm, Rutgers University, Hill 705
Dima Sinapova, Rutgers
Mutual stationarity and the failure of SCH



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



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


On Sun, Sep 24, 2023 at 10:39 PM Jonas Reitz <jonasreitz@gmail.com> wrote:
This Week in Logic at CUNY:

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

NO CLASSES AT CUNY TODAY

Rutgers Logic Seminar
Monday, Sept 25th, 3:30pm, Rutgers University, Hill 705
Dima Sinapova, Rutgers
Mutual stationarity and the failure of SCH



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



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

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

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





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



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

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

Is the consistency operator canonical?

It is a well-known empirical phenomenon that natural axiomatic theories are well-ordered by consistency strength. The restriction to natural theories is necessary; using ad-hoc techniques (such as self-reference and Rosser orderings) one can exhibit non-linearity and ill-foundedness in the consistency strength hierarchy. What explains the contrast between natural theories and axiomatic theories in general?

Our approach to this problem is inspired by work on an analogous problem in recursion theory. The natural Turing degrees  are well-ordered by Turing reducibility, yet the Turing degrees in general are neither linearly ordered nor well-founded, as ad-hoc techniques (such as the priority method) bear out. Martin's Conjecture, which is still unresolved, is a proposed explanation for this phenomenon. In particular, Martin’s Conjecture specifies a way in which the Turing jump is canonical.

After discussing Martin’s Conjecture, we will formulate analogous proof-theoretic hypotheses according to which the consistency operator is canonical. We will then discuss results - both positive and negative - within this framework. Some of these results were obtained jointly with Antonio Montalbán.



Next Week in Logic at CUNY:

- - - - Monday, Oct 2, 2023 - - - -

Rutgers Logic Seminar
Monday, Oct 2nd, 3:30pm, Rutgers University, Hill 705
Philip Stetson, Rutgers
Characterizing LEF groups


Logic and Metaphysics Workshop
Date: Monday, Oct 2, 4.15-6.15pm (NY time)
Room: Graduate Center Room 4419
For meeting information, please sign up for our mailing list at https://logic.commons.gc.cuny.edu/about/
Brett Topey (Salzburg)
Title: Whence admissibility constraints? From inferentialism to tolerance

Abstract: Prior’s invented connective ‘tonk’ is sometimes taken to reveal a problem for certain inferentialist approaches to metasemantics: according to such approaches, the truth-theoretic features of our expressions are fully determined by the rules of inference we’re disposed to follow, but admitting the ‘tonk’ rules into a language would lead to intuitively absurd results. Inferentialists tend to insist that they can avoid these results: there are constraints on what sets of inference rules can be admitted into a language, the story goes, and the rules governing disruptive expressions like ‘tonk’ are defective and so illegitimate. I argue, though, that from an inferentialist perspective, there’s no genuine sense in which rules like the ‘tonk’ rules are defective; those who endorse the relevant sort of inferentialism turn out to be committed to Carnap’s principle of tolerance. I then sketch an argument to the effect that this, despite appearances, isn’t a problem for inferentialism.



- - - - Tuesday, Oct 3, 2023 - - - -



- - - - Wednesday, Oct 4, 2023 - - - -



- - - - Thursday, Oct 5, 2023 - - - -



- - - - Friday, Oct 6, 2023 - - - -

Logic Workshop
CUNY Graduate Center
Friday Sept 29, 2:00pm-3:30pm, Room 6417

Jenna Zomback, University of Maryland
Ergodic theorems along trees

In the classical pointwise ergodic theorem for a probability measure preserving (pmp) transformation , one takes averages of a given integrable function over the intervals  in front of the point . We prove a “backward” ergodic theorem for a countable-to-one pmp , where the averages are taken over subtrees of the graph of  that are rooted at  and lie behind  (in the direction of ). Surprisingly, this theorem yields forward ergodic theorems for countable groups, in particular, one for pmp actions of free groups of finite rank, and can be extended to yield ergodic theorems for pmp actions of free semigroups as well. In each case, the averages are taken along subtrees of the standard Cayley graph rooted at the identity. This is joint work with Anush Tserunyan.




- - - - Other Logic News - - - -

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

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

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

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


- - - - Web Site - - - -

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

--------  ADMINISTRIVIA  --------

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

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

This Week in Logic at CUNY

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

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

NO CLASSES AT CUNY TODAY

Rutgers Logic Seminar
Monday, Sept 25th, 3:30pm, Rutgers University, Hill 705
Dima Sinapova, Rutgers
Mutual stationarity and the failure of SCH



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



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

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

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





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



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

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

Is the consistency operator canonical?

It is a well-known empirical phenomenon that natural axiomatic theories are well-ordered by consistency strength. The restriction to natural theories is necessary; using ad-hoc techniques (such as self-reference and Rosser orderings) one can exhibit non-linearity and ill-foundedness in the consistency strength hierarchy. What explains the contrast between natural theories and axiomatic theories in general?

Our approach to this problem is inspired by work on an analogous problem in recursion theory. The natural Turing degrees  are well-ordered by Turing reducibility, yet the Turing degrees in general are neither linearly ordered nor well-founded, as ad-hoc techniques (such as the priority method) bear out. Martin's Conjecture, which is still unresolved, is a proposed explanation for this phenomenon. In particular, Martin’s Conjecture specifies a way in which the Turing jump is canonical.

After discussing Martin’s Conjecture, we will formulate analogous proof-theoretic hypotheses according to which the consistency operator is canonical. We will then discuss results - both positive and negative - within this framework. Some of these results were obtained jointly with Antonio Montalbán.



Next Week in Logic at CUNY:

- - - - Monday, Oct 2, 2023 - - - -

Rutgers Logic Seminar
Monday, Oct 2nd, 3:30pm, Rutgers University, Hill 705
Philip Stetson, Rutgers
Characterizing LEF groups


Logic and Metaphysics Workshop
Date: Monday, Oct 2, 4.15-6.15pm (NY time)
Room: Graduate Center Room 4419
For meeting information, please sign up for our mailing list at https://logic.commons.gc.cuny.edu/about/
Brett Topey (Salzburg)
Title: Whence admissibility constraints? From inferentialism to tolerance

Abstract: Prior’s invented connective ‘tonk’ is sometimes taken to reveal a problem for certain inferentialist approaches to metasemantics: according to such approaches, the truth-theoretic features of our expressions are fully determined by the rules of inference we’re disposed to follow, but admitting the ‘tonk’ rules into a language would lead to intuitively absurd results. Inferentialists tend to insist that they can avoid these results: there are constraints on what sets of inference rules can be admitted into a language, the story goes, and the rules governing disruptive expressions like ‘tonk’ are defective and so illegitimate. I argue, though, that from an inferentialist perspective, there’s no genuine sense in which rules like the ‘tonk’ rules are defective; those who endorse the relevant sort of inferentialism turn out to be committed to Carnap’s principle of tolerance. I then sketch an argument to the effect that this, despite appearances, isn’t a problem for inferentialism.



- - - - Tuesday, Oct 3, 2023 - - - -



- - - - Wednesday, Oct 4, 2023 - - - -



- - - - Thursday, Oct 5, 2023 - - - -



- - - - Friday, Oct 6, 2023 - - - -

Logic Workshop
CUNY Graduate Center
Friday Sept 29, 2:00pm-3:30pm, Room 6417

Jenna Zomback, University of Maryland
Ergodic theorems along trees

In the classical pointwise ergodic theorem for a probability measure preserving (pmp) transformation , one takes averages of a given integrable function over the intervals  in front of the point . We prove a “backward” ergodic theorem for a countable-to-one pmp , where the averages are taken over subtrees of the graph of  that are rooted at  and lie behind  (in the direction of ). Surprisingly, this theorem yields forward ergodic theorems for countable groups, in particular, one for pmp actions of free groups of finite rank, and can be extended to yield ergodic theorems for pmp actions of free semigroups as well. In each case, the averages are taken along subtrees of the standard Cayley graph rooted at the identity. This is joint work with Anush Tserunyan.




- - - - Other Logic News - - - -

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

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

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

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


- - - - Web Site - - - -

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

--------  ADMINISTRIVIA  --------

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

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

Wednesday seminar

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

Wednesday seminar

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

This Week in Logic at CUNY

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

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

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

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




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

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




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



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



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

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

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



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

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




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

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

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




Next Week in Logic at CUNY:

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



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



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

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

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





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



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

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


- - - - Other Logic News - - - -

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

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

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

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


- - - - Web Site - - - -

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

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

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

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

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

This Week in Logic at CUNY

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

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

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



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

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


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



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



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



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

NO CLASSES - Rosh Hashanah



Next Week in Logic at CUNY:

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

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

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




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



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



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



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

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




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

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

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





- - - - Other Logic News - - - -


- - - - Web Site - - - -

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

--------  ADMINISTRIVIA  --------

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

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

Wednesday seminar

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

Logic Seminars next week

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

Logic Seminar Today

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

This Week in Logic at CUNY

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

Best,
Jonas Reitz



This Week in Logic at CUNY:

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

COLLEGE CLOSED - Labor Day

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



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



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



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

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

Hans Schoutens, CUNY
The model-theory of compact spaces

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



Next Week in Logic at CUNY:

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

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

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


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



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



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



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

NO CLASSES - Rosh Hashanah




- - - - Other Logic News - - - -


- - - - Web Site - - - -

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

--------  ADMINISTRIVIA  --------

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

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

(KGRC) talks for the upcoming semester

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

Wednesday seminar

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

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

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

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

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

Fwd: Aviles

Wrocław Set Theory Seminar


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


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

Wednesday seminar

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

Wednesday seminar

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

Wednesday seminar

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

Wednesday seminar

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

Wednesday seminar

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

RIMS Set Theory Workshop: October 24-27, 2023

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

Wednesday seminar

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

(KGRC) two talks on Thursday, June 29

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

Nankai Logic Colloquium

Nankai Logic Colloquium
Hello everyone,

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

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

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

Best wishes,
Ming Xiao

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

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

Wednesday seminar

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

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

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

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

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

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

Cordialmente:

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

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


Enlace de las conferencias:




 

(KGRC) TU Wien Mini Workshop and two KGRC talks

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

Cross-Alps Logic Seminar (speaker: André Nies)

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

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

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

All the best,
Vincenzo

Set Theory and Topology Seminar 13.06.2023 Paweł Krupski

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

Paweł Krupski


Feel free to spread this information among Your colleagues.

I'm looking forward to seeing You
Szymon Żeberski

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


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

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

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

Nankai Logic Colloquium

Nankai Logic Colloquium

Hello everyone,

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

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

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

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


__________________________________________________________________________________________________

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

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

Zoom Number :893 1745 8343

Passcode : 283146

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

_____________________________________________________________________


Best wishes,

Ming Xiao





Cross-Alps Logic Seminar (speaker: Ulrich Kohlenbach)

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

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

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

All the best,
Vincenzo

Nankai Logic Colloquium

Nankai Logic Colloquium

Hello everyone,

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

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

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

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

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

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

__________________________________________________________________________________________________

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

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

Zoom Number : 876 3579 6414

Passcode : 318535

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

_____________________________________________________________________


Best wishes,

Ming Xiao





Set Theory and Topology Seminar 6.06.2023 Piotr Szewczak (UKSW)

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

Piotr Szewczak (UKSW)


Feel free to spread this information among Your colleagues.

I'm looking forward to seeing You
Szymon Żeberski

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


Abstract

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


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


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

Nankai Logic Colloquium

Nankai Logic Colloquium

Hello everyone,

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

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


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

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

__________________________________________________________________________________________________

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

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

Zoom Number : 851 5601 8255

Passcode : 136440

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

_____________________________________________________________________


Best wishes,

Ming Xiao





Set Theory and Topology Seminar 30.05.2023 Zbigniew Lipecki

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

Zbigniew Lipecki (IM PAN)


Feel free to spread this information among Your colleagues.

I'm looking forward to seeing You
Szymon Żeberski

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


Abstract

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


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


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

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

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

Seminario Colombo Mexicano de Teoría de Conjuntos

Seminario Colombo Mexicano de Teoría de Conjuntos

 

May 25

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


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

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

Zoom meeting information.

Meeting ID: 856 1882 0721

Passcode: 123456

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


This Week in Logic at CUNY

This Week in Logic at CUNY
Hi everyone,

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

Be well,
Jonas


This Week in Logic at CUNY:

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



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

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


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



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



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





- - - - Other Logic News - - - -


- - - - Web Site - - - -

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

--------  ADMINISTRIVIA  --------

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

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

(KGRC) four talks, long and short

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

Set Theory and Topology Seminar 23.05.2023 Barnabas Farkas

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

Barnabas Farkas (TU Wien)


Feel free to spread this information among Your colleagues.

I'm looking forward to seeing You
Szymon Żeberski

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


Abstract

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

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


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

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

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

Seminario Colombo Mexicano de Teoría de Conjuntos

Seminario Colombo Mexicano de Teoría de Conjuntos

 

Mayo 18

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

 

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

Alfredo Zaragoza
Universidad Michoacana de San Nicolás de Hidalgo

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

 

Zoom meeting information.

Meeting ID: 856 1882 0721

Passcode: 123456

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


Cross-Alps Logic Seminar (speaker: Jacques Duparc)

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

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

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

All the best,
Vincenzo

Nankai Logic Colloquium

Nankai Logic Colloquium

Hello everyone,

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

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

Title: A surjection from square onto power


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

__________________________________________________________________________________________________

Title The 29th Nankai Logic Colloquium --Guozhen Shen

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

Zoom Number 856 2849 0880

Passcode  073635

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

_____________________________________________________________________


Best wishes,

Ming Xiao





This Week in Logic at CUNY

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

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

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

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

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





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



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

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

Speaker:     Arthur Parzygnat, Nagoya University.

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

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


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





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



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

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

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

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




Next Week in Logic at CUNY:

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



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

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


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



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



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





- - - - Other Logic News - - - -


- - - - Web Site - - - -

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

--------  ADMINISTRIVIA  --------

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

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

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

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

Nankai Logic Colloquium

Nankai Logic Colloquium

lHello everyone,

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

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

Title: Continuous logic and equivalence relations

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


__________________________________________________________________________________________________

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

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


Best wishes,

Ming Xiao




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

Seminario Colombo Mexicano de Teoría de Conjuntos

Seminario Colombo Mexicano de Teoría de Conjuntos

 

Mayo 11

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

 

Construcciones conjuntistas en modelos valuados y de Kripke

Jose R. Moncayo

Universidad Nacional de Colombia

 

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

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

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

 

Zoom meeting information.

Meeting ID: 856 1882 0721

Passcode: 123456

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


This Week in Logic at CUNY

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

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

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

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

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

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

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




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

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

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

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

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

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






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

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

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

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

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

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

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





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

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

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

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

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

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

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

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


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



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

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

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

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



Next Week in Logic at CUNY:

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

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

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

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





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



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

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

Speaker:     Arthur Parzygnat, Nagoya University.

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

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


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





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



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

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

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

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






- - - - Other Logic News - - - -


- - - - Web Site - - - -

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

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

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

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

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

Wednesday seminar

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

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

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

Cross-Alps Logic Seminar (speaker: Dima Sinapova)

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

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

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

All the best,
Vincenzo

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

Seminario Colombo Mexicano de Teoría de Conjuntos

Seminario Colombo Mexicano de Teoría de Conjuntos

 

Mayo 4

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

 

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

Joel Aguilar

Universidad Michoacana de San Nicolás de Hidalgo

 

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

 

Zoom meeting information.

Meeting ID: 856 1882 0721

Passcode: 123456

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


Nankai Logic Colloquium

Nankai Logic Colloquium

Hello everyone,

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

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

_____________________________________________________

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

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

Title:  Corona rigidity


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

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

__________________________________________________________________________________________________

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

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


Best wishes,

Ming Xiao






Wednesday seminar

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

Nankai Logic Colloquium

Nankai Logic Colloquium

Hello everyone,

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

The following is a corrected version of the previous email:

_____________________________________________________

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

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

Title:  Corona rigidity


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

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

__________________________________________________________________________________________________

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

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


Best wishes,

Ming Xiao





Nankai Logic Colloquium

Nankai Logic Colloquium

Hello everyone,

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

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

Title:  Corona rigidity


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

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

__________________________________________________________________________________________________

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

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


Best wishes,

Ming Xiao




This Week in Logic at CUNY

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

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

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

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



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



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

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

Speaker:     Gemma De las Cuevas, University of Innsbruck.

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

Title:     A framework for universality across disciplines.


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





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



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

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

Realizing Frege's Basic Law V, provably in ZFC

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



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

Classification via effective lists

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



Next Week in Logic at CUNY:

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

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

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

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

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

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




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

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

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

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

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

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






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

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

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

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

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

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

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





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

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

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

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

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

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

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

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


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



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

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

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

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



- - - - Other Logic News - - - -

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

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



- - - - Web Site - - - -

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

--------  ADMINISTRIVIA  --------

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(KGRC) two talks on Thursday, May 4

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

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

Seminario Colombo Mexicano de Teoría de Conjuntos

Seminario Colombo Mexicano de Teoría de Conjuntos

 

Abril 27

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

 

Cardinales característicos en el caso no enumerable
Diana C. Montoya

Universidad Técnica de Viena

 

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


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

Nankai Logic Colloquium

Nankai Logic Colloquium

Hello everyone,

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

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

Title: Topology versus Borel structure for actions

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