Set Theory Talks

This Week in Logic at CUNY

9/15/2024 22:37:00

This Week in Logic at CUNY:

- - - - Monday, Sep 16, 2024 - - - -

Rutgers Logic Seminar
Monday September 16, 3:30pm, Rutgers University, Hill Center, Hill 705
Maxwell Levine, University of Freiburg
Namba Forcing, Minimality, and Approximations

Logic and Metaphysics Workshop
Date: Monday,September 16, 4.15-6.15pm (NY time)
Room: Graduate Center Room 4419
Speaker: Mel Fitting (CUNY)
Title: Simple tableaus for simple logics

Abstract: Consider those many-valued logic models in which the truth values are a lattice that supplies interpretations for the logical connectives of conjunction and disjunction, and which has a De Morgan involution supplying an interpretation for negation. Assume the set of designated truth values is a prime filter in the lattice. Each of these structures determines a simple many-valued logic. We show there is a single Smullyan style signed tableau system appropriate for all of the logics these structures determine. Differences between the logics are confined entirely to tableau branch closure rules. Completeness, soundness, and interpolation can be proved in a uniform way for all cases. Since branch closure rules have a limited number of variations, in fact all the semantic structures determine just four different logics, all well-known ones. Asymmetric logics such as strict/tolerant, ST, also share all the same tableau rules, but differ in what constitutes an initial tableau. It is also possible to capture the notion of anti-validity using the same set of tableau rules. Thus a simple set of tableau rules serves as a unifying and classifying device for a natural and simple family of many-valued logics.

- - - - Tuesday, Sep 17, 2024 - - - -

- - - - Wednesday, Sep 18, 2024 - - - -

The New York City Category Theory Seminar
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York
Date and Time: Wednesday September 18, 2024, 7:00 - 8:30 PM. IN-PERSON TALK, Room 6417

Speaker: Jake Araujo-Simon, Cornell Tech.

Title: Categorifying the Volterra series: towards a compositional theory of nonlinear signal processing.

Abstract:The Volterra series is a model of nonlinear behavior that extends the convolutional representation of linear and time-invariant systems to the nonlinear regime. Though well-known and applied in electrical, mechanical, biomedical, and audio engineering, its abstract and especially compositional properties have been less studied. In this talk, we present an approach to categorifying the Volterra series, in which a Volterra series is defined as a functor on a category of signals and linear maps, a morphism between Volterra series is a lens map and natural transformation, and together, Volterra series and their morphisms assemble into a category, which we call Volt. We study three monoidal structures on Volt, and outline connections of our work to the field of time-frequency analysis. We also include an audio demo.

Paper link: https://arxiv.org/abs/2308.07229

- - - - Thursday, Sep 19, 2024 - - - -

- - - - Friday, Sep 20, 2024 - - - -

Next Week in Logic at CUNY:

- - - - Monday, Sep 23, 2024 - - - -

Rutgers Logic Seminar
Monday September 9, 3:30pm, Rutgers University, Hill Center, Hill 705

Russell Miller, CUNY
Countable reductions in computable structure theory

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

Rohit Parikh (CUNY)
Title: Value and freedom

Abstract: In order to decide how good a society is, we need some measure of goodness. And the goodness of a society is typically obtained by somehow summing up the well beings of its members. Various approaches include Utilitarianism and Rawlsianism as well as the Leximin approach suggested by Amartya Sen. But Sen and Nussbaum have suggested that the Capability of an individual, what the individual can do, should be the real measure of well being. Another issue is that of freedom. My freedom can be diminished by some restrictive laws. But it can also be diminished by some handicap, or by certain social methods not being available. How to measure the amount of freedom I have? Is it simply the number of options I have, or does the value of the options also matter? And what is the mathematics of freedom?

Note: An extended abstract is available here.

- - - - Tuesday, Sep 24, 2024 - - - -

- - - - Wednesday, Sep 25, 2024 - - - -

The New York City Category Theory Seminar
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York
Date and Time: Wednesday September 25, 2024, 7:00 - 8:30 PM. IN-PERSON TALK, Room 6417

Speaker: Noah Chrein, University of Maryland

Title: A formal category theory for oo-T-multicategories.

Abstract: We will explore a framework for oo-T-multicategories. To begin, we build a schema for multicategories out of the simplex schema and the monoid schema. The multicategory schema, D_m, inherits the structure of a monad from the +1 monad on the monoid schema. Simplicial T-multicategories are monad preserving functors out of the multicategory schema, [D_m, T], into another monad T. The framework is larger than just [D_m,T]. A larger structure describes notions of yoneda lemma and fibration. Inner fibrant, simplicial T-multicategories are oo-T-multicategories. oo-T-multicategories generalize oo-categories and oo-operads: oo-operads are fm-multicategories, oo-categories are Id-multicategories.

We use this framework to study oo-fc-multicategories, or "oo - virtual double categories". In general, under various assumptions on T (which hold for fc), the collection of oo-T-multicategories [D_m, T] has other useful structure. One such structure is a join operation. This join operation points towards a synthetic definition of op/cartesian cells, which we hope will model oo-virtual equipments. If there is time, I will explain the motivation for this study as it relates to ontologies, meta-theories and type theories.

- - - - Thursday, Sep 26, 2024 - - - -

- - - - Friday, Sep 27, 2024 - - - -

Logic Workshop
CUNY Graduate Center
Friday September 27, 2:00pm-3:30pm, Room 4419

Victoria Gitman, CUNY

TBA

- - - - Other Logic News - - - -

- - - - Web Site - - - -

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

-------- ADMINISTRIVIA --------

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

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

Logic Seminar 18 September 2024 16:45 hrs at NUS by Le Quy Thuong

NUS Logic Seminar

9/15/2024 22:49:51

Invitation to the Logic Seminar at the National University of Singapore Date: Wednesday, 18 September 2024, 16:45 hrs Place: NUS, Department of Mathematics, S17#04-04 Speaker: Le Quy Thuong Title: Motivic integration in valued fields and applications to singularity theory Abstract: Since 1995, motivic integration has been a powerful tool in algebraic geometry and other branches of mathematics. In particular, it has many important applications to singularity theory. For instance, Denef-Loeser around 2000 gave a breakthrough point of view in the study of singularities, by introducing the so-called motivic Milnor fiber, with the philosophy that this is a motivic incarnation of the classical Milnor fiber. One shows that many singularity invariants can be easily recovered from motivic zeta function and motivic Milnor fiber employing an appropriate Hodge realization. Furthermore, there are important problems concerning singularity theory such as monodromy conjecture, the integral identity conjecture, and the Thom-Sebastiani theorem that are waiting for new methods in motivic integration to have a solution. In this talk, we will describe some surprising interactions between motivic integration, model theory and singularity theory that lead to our proofs for the integral identity conjecture, and the motivic Thom-Sebastiani theorem, as well as other applications to singularities. The talk will avoid technical aspects and emphasize key ideas in motivic integration and singularity theory, which may be friendly to a general audience. Note that this week the seminar starts 15 minutes earlier than usual. URL: http://www.comp.nus.edu.sg/~fstephan/logicseminar.html

This Week in Logic at CUNY

9/8/2024 22:47:00

This Week in Logic at CUNY:

- - - - Monday, Sep 9, 2024 - - - -

Rutgers Logic Seminar
Monday September 9, 3:30pm Hill Center, Hill 705
Corey Switzer, KGRC
Weak and Strong Variants of Baumgartner's Axiom for Polish Spaces

Logic and Metaphysics Workshop
Date: Monday,September 9, 4.15-6.15pm (NY time)
Room: Graduate Center Room 4419
Speaker: Hartry Field (NYU)
Title: Well-behaved truth

Abstract: Common-sense reasoning with truth involves both the use of classical logic and the assumption of the transparency of truth (the equivalence between a sentence and the attribution of truth to it). The semantic paradoxes show that at least one of these must go, and different theorists make different choices. But whatever one’s choice, it’s valuable to carve out one or more domains where both classical logic and transparency can be assumed; domains where everything is *well-behaved*. In this talk I’ll explore a method of adding a predicate of well-behavedness to various truth theories, which works for both classical and nonclassical theories (including non-classical theories with special conditionals). With such a predicate, one can reason more easily, and formulate and prove generalizations that are unavailable without such a predicate. Besides their intrinsic interest, these generalizations greatly increase the proof-theoretic strength of axiomatic theories. (There are some previous proposals for adding a well-behavedness predicate to specific classical theories, and others for adding one to non-classical theories without special conditionals. The current proposal, besides being general, is also more satisfactory in the individual cases, and is the only one I know of for non-classical theories with conditionals.)

- - - - Tuesday, Sep 10, 2024 - - - -

- - - - Wednesday, Sep 11, 2024 - - - -

- - - - Thursday, Sep 12, 2024 - - - -

- - - - Friday, Sep 13, 2024 - - - -

Logic Workshop
CUNY Graduate Center
Friday September 13, 2:00pm-3:30pm, Room 4419

David Marker, University of Illinois at Chicago
Rigid real closed fields

Shelah showed that it is consistent that there are uncountable rigid non-archimedean real closed fields and, later, he and Mekler proved this in . Answering a question of Enayat, Charlie Steinhorn and I show that there are countable rigid non-archimedean real closed fields by constructing one of transcendence degree two.

Next Week in Logic at CUNY:

- - - - Monday, Sep 16, 2024 - - - -

Rutgers Logic Seminar
Monday September 9, 3:30pm, Rutgers University, Hill Center, Hill 705
Maxwell Levine, University of Freiburg
Namba Forcing, Minimality, and Approximations

Logic and Metaphysics Workshop
Date: Monday,September 16, 4.15-6.15pm (NY time)
Room: Graduate Center Room 4419
Speaker: Mel Fitting (CUNY)
Title: Simple tableaus for simple logics

Abstract: Consider those many-valued logic models in which the truth values are a lattice that supplies interpretations for the logical connectives of conjunction and disjunction, and which has a De Morgan involution supplying an interpretation for negation. Assume the set of designated truth values is a prime filter in the lattice. Each of these structures determines a simple many-valued logic. We show there is a single Smullyan style signed tableau system appropriate for all of the logics these structures determine. Differences between the logics are confined entirely to tableau branch closure rules. Completeness, soundness, and interpolation can be proved in a uniform way for all cases. Since branch closure rules have a limited number of variations, in fact all the semantic structures determine just four different logics, all well-known ones. Asymmetric logics such as strict/tolerant, ST, also share all the same tableau rules, but differ in what constitutes an initial tableau. It is also possible to capture the notion of anti-validity using the same set of tableau rules. Thus a simple set of tableau rules serves as a unifying and classifying device for a natural and simple family of many-valued logics.

- - - - Tuesday, Sep 17, 2024 - - - -

- - - - Wednesday, Sep 18, 2024 - - - -

The New York City Category Theory Seminar
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York
Date and Time: Wednesday September 18, 2024, 7:00 - 8:30 PM. IN-PERSON TALK
Room 5417 (not the usual Room 6417)

Speaker: Jake Araujo-Simon, Cornell Tech.

Title: Categorifying the Volterra series: towards a compositional theory of nonlinear signal processing.

- - - - Thursday, Sep 19, 2024 - - - -

- - - - Friday, Sep 20, 2024 - - - -

- - - - 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.

UPDATE: This Week in Logic - today's Logic Workshop is in GC 4419

This Week in Logic at CUNY

9/6/2024 7:16:03

Please note, the room for the Logic Workshop, including today's talk at has been changed to 4419.

Best,

Jonas

This Week in Logic at CUNY:

- - - - Thursday, Sep 05, 2024 - - - -

- - - - Friday, Sep 06, 2024 - - - -

Set Theory Seminar
CUNY Graduate Center
Friday, September 6, 11:00am NY time
Virtual: Please email Victoria Gitman (vgitman@gmail.com) for zoom info.

Corey Switzer, Kurt Gödel Research Center
Reflecting Ordinals and Forcing

Let and either or . An ordinal is called -reflecting if for each and each -formula if then there is a so that where here refers to full second order logic. The least -reflecting ordinal is called and the least -ordinal is called . These ordinals provably exist and are countable (for all ). They 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 then for all we have (due to Cutland) while under PD for all we have if and only if is even (due to Kechris).
Surprisingly nothing was known about these ordinals in any model which satisfies neither 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 about which ordinals are -reflecting (for any and ). Meanwhile, in the generic extension by collapsing many interesting things happen, not least amongst them that and are increased - yet still below for . Along the way we will discuss the plethora of open problems in this area. This is joint work with Juan Aguilera.

Logic Workshop
CUNY Graduate Center
Friday September 6, 2:00pm-3:30pm, Room 4419

Corey Switzer, Kurt Gödel Research Center
Weak and Strong Variants of Baumgartner's Axiom for Polish Spaces

(One version of) Cantor's second best theorem states that every pair of countable, dense sets of reals are isomorphic as linear orders. From the perspective of set theory it's natural to ask whether some variant of this theorem can hold consistently when 'countable' is replaced by 'uncountable'. This was shown in the affirmative by Baumgartner in 1973 who showed the consistency of 'all -dense sets of reals are order isomorphic' where a set is -dense for a cardinal if its intersection with any open interval has size . The above became known as Baumgartner's axiom, denoted BA, and is an important axiom in both combinatorial set theory and set theoretic topology. BA has natural higher dimensional analogues - i.e., statements with the same relation to that BA has to . It is a long standing open conjecture of Steprāns and Watson that BA implies its higher dimensional analogues.

In the talk I will describe some attempts to break the ice on this open problem mostly by looking at a family of weaker and stronger variants of BA and investigating their combinatorial, analytic and topological consequences. We will show that while some weak variants of BA have all the same consequences as BA, even weaker ones do not. Meanwhile a strengthening of BA for Baire and Polish space gives much more information.

Next Week in Logic at CUNY:

- - - - Monday, Sep 9, 2024 - - - -

Rutgers Logic Seminar
Monday September 9, 3:30pm Hill Center, Hill 705
Corey Switzer, KGRC
Weak and Strong Variants of Baumgartner's Axiom for Polish Spaces

Logic and Metaphysics Workshop
Date: Monday,September 9, 4.15-6.15pm (NY time)
Room: Graduate Center Room 4419
Speaker: Hartry Field (NYU)
Title: Well-behaved truth

Abstract: Common-sense reasoning with truth involves both the use of classical logic and the assumption of the transparency of truth (the equivalence between a sentence and the attribution of truth to it). The semantic paradoxes show that at least one of these must go, and different theorists make different choices. But whatever one’s choice, it’s valuable to carve out one or more domains where both classical logic and transparency can be assumed; domains where everything is *well-behaved*. In this talk I’ll explore a method of adding a predicate of well-behavedness to various truth theories, which works for both classical and nonclassical theories (including non-classical theories with special conditionals). With such a predicate, one can reason more easily, and formulate and prove generalizations that are unavailable without such a predicate. Besides their intrinsic interest, these generalizations greatly increase the proof-theoretic strength of axiomatic theories. (There are some previous proposals for adding a well-behavedness predicate to specific classical theories, and others for adding one to non-classical theories without special conditionals. The current proposal, besides being general, is also more satisfactory in the individual cases, and is the only one I know of for non-classical theories with conditionals.)

- - - - Tuesday, Sep 10, 2024 - - - -

- - - - Wednesday, Sep 11, 2024 - - - -

- - - - Thursday, Sep 12, 2024 - - - -

- - - - Friday, Sep 13, 2024 - - - -

Logic Workshop
CUNY Graduate Center
Friday September 13, 2:00pm-3:30pm, Room 4419

David Marker, University of Illinois at Chicago
Rigid real closed fields

Shelah showed that it is consistent that there are uncountable rigid non-archimedean real closed fields and, later, he and Mekler proved this in . Answering a question of Enayat, Charlie Steinhorn and I show that there are countable rigid non-archimedean real closed fields by constructing one of transcendence degree two.

- - - - 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.

Logic Seminar 11 September 2024 17:00 hrs by Kihara Takayuki at NUS

NUS Logic Seminar

9/6/2024 5:50:14

Invitation to the Logic Seminar at the National University of Singapore Date: Wednesday, 11 September 2024, 17:00 hrs Place: NUS, Department of Mathematics, S17#04-04 Speaker: Kihara Takayuki Title: Degrees of unsolvability of natural problems: A realizability-theoretic approach Abstract: The theories of degrees of unsolvability and realizability interpretation both have long histories, having both been born in the 1940s. S. C. Kleene was a key figure who led the development of both theories. Despite having been developed by the same person, there seems to have been little deep mixing of these theories until recently. In this talk, we will reconstruct the theory of degrees of unsolvability from the perspective of realizability theory. URL: http://www.comp.nus.edu.sg/~fstephan/logicseminar.html

Wednesday seminar

Prague Set Theory Seminar

9/5/2024 9:34:21

Dear all, The seminar meets on Wednesday September 11th at 11:00 in the Institute of Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building. Program: Pedro Marun -- Labelled sets A theorem of Dilworth asserts that, if a poset P has no antichains of size m+1, where m is a natural number, then P can be written as a union of m many chains. If m is instead an infinite cardinal, then the analogous statement is false, counterexamples were constructed by Perles. In recent work, Abraham and Pouzet gave a basis for the class of such counterexamples, and asked if it could be somewhat simplified. Labelled sets arise in connection with these counterexamples. We show that, when the underlying sets are aleph_1-dense, then any two labelled sets embed into each other. Best, David

This Week in Logic at CUNY

9/4/2024 23:26:44

This initial edition of This Week in Logic at CUNY is going out midweek, but in future our mailings will be on Sunday evenings as in the past. Welcome back, everyone!

Best,

Jonas

This Week in Logic at CUNY:

- - - - Thursday, Sep 05, 2024 - - - -

- - - - Friday, Sep 06, 2024 - - - -

Set Theory Seminar
CUNY Graduate Center
Friday, September 6, 11:00am NY time
Virtual: Please email Victoria Gitman (vgitman@gmail.com) for zoom info.

Corey Switzer, Kurt Gödel Research Center
Reflecting Ordinals and Forcing

Let $n < ω$ and $Γ$ either $Π$ or $Σ$ . An ordinal $α$ is called $Γ 1 n$ -reflecting if for each $β < α$ and each $Γ 1 n$ -formula $φ$ if $L α ⊨ φ (β)$ then there is a $γ \in (β, α)$ so that $L γ ⊨ φ (β)$ where here $⊨$ refers to full second order logic. The least $Σ 1 n$ -reflecting ordinal is called $σ 1 n$ and the least $Π 1 n$ -ordinal is called $π 1 n$ . These ordinals provably exist and are countable (for all $n < ω$ ). They 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 $n < ω$ we have $σ 1 n + 3 < π 1 n + 3$ (due to Cutland) while under PD for all $n < ω$ we have $σ 1 n < π 1 n$ 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 $Γ 1 n$ -reflecting (for any $n$ and $Γ$ ). Meanwhile, in the generic extension by collapsing $ω 1$ many interesting things happen, not least amongst them that $σ 1 n$ and $π 1 n$ are increased - yet still below $ω L 1$ for $n > 2$ . Along the way we will discuss the plethora of open problems in this area. This is joint work with Juan Aguilera.

Logic Workshop
CUNY Graduate Center
Friday September 6, 2:00pm-3:30pm, Room 6417 (NOTICE THE CHANGE! BACK TO OUR PRE-2023 ROOM)

Corey Switzer, Kurt Gödel Research Center
Weak and Strong Variants of Baumgartner's Axiom for Polish Spaces

(One version of) Cantor's second best theorem states that every pair of countable, dense sets of reals are isomorphic as linear orders. From the perspective of set theory it's natural to ask whether some variant of this theorem can hold consistently when 'countable' is replaced by 'uncountable'. This was shown in the affirmative by Baumgartner in 1973 who showed the consistency of 'all $ℵ 1$ -dense sets of reals are order isomorphic' where a set is $κ$ -dense for a cardinal $κ$ if its intersection with any open interval has size $κ$ . The above became known as Baumgartner's axiom, denoted BA, and is an important axiom in both combinatorial set theory and set theoretic topology. BA has natural higher dimensional analogues - i.e., statements with the same relation to $R n$ that BA has to $R$ . It is a long standing open conjecture of Steprāns and Watson that BA implies its higher dimensional analogues.

In the talk I will describe some attempts to break the ice on this open problem mostly by looking at a family of weaker and stronger variants of BA and investigating their combinatorial, analytic and topological consequences. We will show that while some weak variants of BA have all the same consequences as BA, even weaker ones do not. Meanwhile a strengthening of BA for Baire and Polish space gives much more information.

Next Week in Logic at CUNY:

- - - - Monday, Sep 9, 2024 - - - -

Rutgers Logic Seminar
Monday September 9, 3:30pm Hill Center, Hill 705
Corey Switzer, KGRC
Weak and Strong Variants of Baumgartner's Axiom for Polish Spaces

Logic and Metaphysics Workshop
Date: Monday,September 9, 4.15-6.15pm (NY time)
Room: Graduate Center Room 4419
Speaker: Hartry Field (NYU)
Title: Well-behaved truth

Abstract: Common-sense reasoning with truth involves both the use of classical logic and the assumption of the transparency of truth (the equivalence between a sentence and the attribution of truth to it). The semantic paradoxes show that at least one of these must go, and different theorists make different choices. But whatever one’s choice, it’s valuable to carve out one or more domains where both classical logic and transparency can be assumed; domains where everything is *well-behaved*. In this talk I’ll explore a method of adding a predicate of well-behavedness to various truth theories, which works for both classical and nonclassical theories (including non-classical theories with special conditionals). With such a predicate, one can reason more easily, and formulate and prove generalizations that are unavailable without such a predicate. Besides their intrinsic interest, these generalizations greatly increase the proof-theoretic strength of axiomatic theories. (There are some previous proposals for adding a well-behavedness predicate to specific classical theories, and others for adding one to non-classical theories without special conditionals. The current proposal, besides being general, is also more satisfactory in the individual cases, and is the only one I know of for non-classical theories with conditionals.)

- - - - Tuesday, Sep 10, 2024 - - - -

- - - - Wednesday, Sep 11, 2024 - - - -

- - - - Thursday, Sep 12, 2024 - - - -

- - - - Friday, Sep 13, 2024 - - - -

Logic Workshop
CUNY Graduate Center
Friday September 13, 2:00pm-3:30pm, Room 6417 (NOTICE THE CHANGE! BACK TO OUR PRE-2023 ROOM)

David Marker, University of Illinois at Chicago
Rigid real closed fields

Shelah showed that it is consistent that there are uncountable rigid non-archimedean real closed fields and, later, he and Mekler proved this in $ZFC$ . Answering a question of Enayat, Charlie Steinhorn and I show that there are countable rigid non-archimedean real closed fields by constructing one of transcendence degree two.

- - - - 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.

Location change -- Wednesday seminar -- Macpherson

Prague Set Theory Seminar

9/3/2024 3:25:24

Dear all, LOCATION CHANGE The seminar tomorrow will take place in the blue lecture hall, ground floor, rear building, Institute of Mathematics CAS, Zitna 25. Time is the same, we meet at 11:00. Best, David On 30/08/2024 14:36, David Chodounsky wrote: > Dear all, > > The seminar meets on Wednesday September 4th at 11:00 in the Institute > of Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building. > > > Program: Dugald Macpherson -- Definable set in finite structures, and > generalised measurable structures > > A result of Chatzidakis, van den Dries and Macintyre says that if > \phi(x,y) is a formula in the language of rings (x,y tuples), then there > are finitely many pairs (\mu,d) (\mu positive rational, d a natural > number) such that for any finite field F_q and parameter a, the set > \phi(F_q,a) has size roughly \mu.q^d for one of the pairs (\mu,d). This > builds on the Lang-Weil estimates for the number of rational points in > an algebraic variety over a finite field. The result ensures that > pseudofinite fields have a notion of measure assigned to definable sets > and satisfying various axioms (such as a Fubini condition) and in > particular that pseudofinite fields have supersimple theory. > > I will describe various generalisations of this result, starting with > work with Steinhorn, extended by Elwes, Ryten and others, and leading > to a further framework from a recent paper with Anscombe, Steinhorn and > Wolf. > > > > Best, > David

Wednesday seminar -- Macpherson

Prague Set Theory Seminar

8/30/2024 8:36:46

Dear all, The seminar meets on Wednesday September 4th at 11:00 in the Institute of Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building. Program: Dugald Macpherson -- Definable set in finite structures, and generalised measurable structures A result of Chatzidakis, van den Dries and Macintyre says that if \phi(x,y) is a formula in the language of rings (x,y tuples), then there are finitely many pairs (\mu,d) (\mu positive rational, d a natural number) such that for any finite field F_q and parameter a, the set \phi(F_q,a) has size roughly \mu.q^d for one of the pairs (\mu,d). This builds on the Lang-Weil estimates for the number of rational points in an algebraic variety over a finite field. The result ensures that pseudofinite fields have a notion of measure assigned to definable sets and satisfying various axioms (such as a Fubini condition) and in particular that pseudofinite fields have supersimple theory. I will describe various generalisations of this result, starting with work with Steinhorn, extended by Elwes, Ryten and others, and leading to a further framework from a recent paper with Anscombe, Steinhorn and Wolf. Best, David

Logic Seminar 28 August 2024 17:00 hrs by Linus Richter, NUS

NUS Logic Seminar

8/23/2024 22:25:58

Invitation to the Logic Seminar at the National University of Singapore Date: Wednesday, 28 August 2024, 17:00 hrs Place: NUS, Department of Mathematics, S17#04-04 Speaker: Linus Richter Title: Definable (Classical) Mathematics URL: http://www.comp.nus.edu.sg/~fstephan/logicseminar.html Abstract: I will outline a few connections between various notions of definability (which vary in degree of logical formality), give examples, and describe some open questions at the intersection of logic and classical mathematics.

Logic Seminar at NUS on 21 Aug 2024 17:00 hrs by Vo Ngoc Thieu

NUS Logic Seminar

8/18/2024 22:42:19

Invitation to the Logic Seminar at the National University of Singapore Date: Wednesday, 21 August 2024, 17:00 hrs Place: NUS, Department of Mathematics, S17#04-04 Speaker: Vo Ngoc Thieu Title: Some Computational Aspects of Differential-Algebraic Equations Abstracts: Let DAE denote ``Differential-Algebraic Equation''. The main aim of this talk is to introduce our recent results on computational problems related to DAEs, including the effective differential Nullstellensatz, effective differential elimination, and finding general solutions of low-order algebraic ODEs. The effective differential Nullstellensatz involves finding a positive integer N for a given DAE system, such that one can check the consistency of the system by performing N differentiations and polynomial eliminations. Differential elimination involves removing independent variables from a DAE system. Differential Nullstellensatz and elimination are two fundamental problems in differential algebra and differential algebraic geometry. Since the number N represents the computational complexity of the effective differential Nullstellensatz and elimination, finding an upper bound for N is crucial. We will present our recent investigations into the problem of determining an upper bound for N. In addition, our results on the problem of determining algebraic/rational general solutions of first-order algebraic ODEs, as well as their connection with the Poincare problem, will also be presented. URL: http://www.comp.nus.edu.sg/~fstephan/logicseminar.html

KGRC talk August 16

Kurt Godel Research Center

08/08/2024

KGRC/Institute of Mathematics invites you to the following talk: Set Theory Seminar Kolingasse 14--16, 1090, 1st floor, SR 10, Friday, August 16, 1:00pm--2:00pm, hybrid mode "Inaccessible cardinals and weak compactness in ZF" H. Duncan (U of Leeds, GB) Symmetric extensions are a generalisation of forcing used to extend models of ZF. We will give an introduction to the technique of symmetric extensions and use them to prove results in ZF. Specifically, we will show that $\omega_1$ can be inaccessible in ZF. We will finally examine weak compactness in ZF, as many weak compactness results which are equivalent in ZFC are not equivalent in ZF. These non equivalences can be shown explicitly at $\omega_1$. Zoom info: If you have not received the Zoom data by the day before the talk, please contact petra.czarnecki@univie.ac.at. Please direct any questions about this talk to vera.fischer@univie.ac.at. * * * Updates at https://kgrc.univie.ac.at/eventsnews/

Logic Seminar 7 August 2024 17:00 hrs at NUS by Zhang Jing

NUS Logic Seminar

8/2/2024 5:00:06

Invitation to the Logic Seminar at the National University of Singapore Date: Wednesday, 7 August 2024, 17:00 hrs Place: NUS, Department of Mathematics, S17#04-04 Speaker: Zhang Jing Title: Higher dimensional combinatorics URL: http://www.comp.nus.edu.sg/~fstephan/logicseminar.html We expose an organizing framework to study higher dimensional infinitary combinatorics based on Cech cohomology, originating from works by Barry Mitchell, Barbara Osofsky and others. Key combinatorial notions include n-coherence and n-triviality for sequences of functions. We will use some recent vanishing and non-vanishing results to demonstrate "aleph_n is incompact for (n+1)-dimensional combinatorics" and "aleph_{omega+1} can be compact for n-dimensional combinatorics for all n". Time permitting, we will also discuss the possibility of generalizing classical 2-dimensional properties like being special or being Suslin to higher dimensions. The talk will be purely combinatorial. This is joint work with Jeffrey Bergfalk and Chris Lambie-Hanson.

Logic Seminar 31 July 2024 17:00 hrs at NUS by George Barmpalias, CAS

NUS Logic Seminar

7/29/2024 2:09:10

Invitation to the Logic Seminar at the National University of Singapore Date: Wednesday, 31 July 2023, 17:00 hrs Place: NUS, Department of Mathematics, S17#04-05 Speaker: George Barmpalias, Institute of Software, Chinese Academy of Sciences Title: Questions and progress in Algorithmic Randomness Abstract: I will discuss current challenges and progress in algorithmic randomness, focusing on Chaitin's halting probability, almost everywhere domination and measures of relative randomness. I will offer conjectures, partial results and benchmark problems toward solving the main questions. URL: http://www.comp.nus.edu.sg/~fstephan/logicseminar.html

Kyoto University RIMS Set Theory Workshop, October 9-11, 2024

Conference

7/15/2024

Kyoto University RIMS Set Theory Workshop 2024 Announcement / Call for Contributions Kyoto University RIMS Workshop: Recent Developments in Axiomatic Set Theory Hybrid workshop Date: Wednesday October 9th to Friday October 11th, 2024 Organizer: Masahiro Shioya (University of Tsukuba) Overview: RIMS Set Theory Workshop is held annually at the Research Institute for Mathematical Sciences, Kyoto University, Japan. It aims to bring together researchers in Set Theory from Japan and abroad and to foster research exchange. We encourage both young researchers and experts to contribute with talks. Any topics in Set Theory and relevant areas, as well as both in-person talks at RIMS and online talks via Zoom, are welcome. Invited Lectures: Monroe Eskew (University of Vienna): Dense ideals Gabriel Goldberg (UC Berkeley): The Ultrapower Axiom Registration through the website https://sites.google.com/view/rims-set-theory-2024/home Registration deadlines: Contributed talks: August 31st, 2024 Attendance in person: August 31st, 2024 Attendance via Zoom: October 7th, 2024

Link to more info

Wednesday seminar

Prague Set Theory Seminar

6/26/2024 9:34:32

Dear all, The seminar meets on Wednesday July 3rd at 11:00 in the Institute of Mathematics CAS, Zitna 25, blue lecture hall, ground floor, rear building. NOTE THE UNUSUAL LOCATION! Program: Jindrich Zapletal -- A convenient axiomatization of the Solovay model I provide a simple forcing-free axiomatization of the choiceless Solovay model, which proves many of its features and features of its generic extensions. It is unlikely that there will be more Wednesday seminars during the rest of July. Seminars in August are uncertain. You might be interested in the Midsummer Combinatorial Workshop which will take place during July 29--August 2nd at Mala Strana, there will be a number of interesting visitors. Best, David

Set theory and topology seminar 25.06.2024 everybody

Wrocław Set Theory Seminar

6/23/2024 6:40:02

I am happy to announce that the last seminar this semester in Set Theory and Topology (on Thuesday 25.06.2024 at 17:15) will take place in

"Forma Płynna Beach Bar"

Plaża miejska, Wybrzeże Wyspiańskiego.

Every participant is the speaker.

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)

Wednesday seminar

Prague Set Theory Seminar

6/21/2024 7:57:55

Dear all, The seminar meets on Wednesday June 26th at 11:00 in the Institute of Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building. Program: Tristan Bice -- Constructing Compacta from Posets Trees are commonly used to construct topological spaces from their branches. However, the resulting spaces are usually quite special, e.g. having lots of clopen sets. Our goal is to construct more general (e.g. connected) spaces in a similar way from posets that are still quite 'tree-like'. This leads to a simple construction allowing us to build any second countable compact T_1 space (e.g. any metrisable compactum) from a countable graded poset with finite levels. In particular, this can be used to construct spaces like the pseudoarc and Lelek fan as Fraïssé limits in appropriate categories of graphs with relational morphisms. Continuous maps can also be encoded by certain relations between the posets with potential applications to finding dense and comeagre conjugacy classes of homeomorphisms, again in a simple Fraïssé theoretic way (joint work with Adam Bartoš, Maciej Malicki and Alessandro Vignati). Best, David

Set theory and topology seminar 18.06.2024 Aleksander Cieślak

Wrocław Set Theory Seminar

6/17/2024 9:14:37

I am happy to announce that at the seminar in set theory and topology (on Tuesday 18.06.2024 at 17:15 in room A.4.1 C-19 (Wrocław University of Science and Technology) the lecture:

"The splitting ideal"

will be presented by

Aleksander Cieślak

Abstract:

We will investigate the cardinal invariants and the Katetov position of certain ideal on \omega. As a result we will obtain a new upper boundary of the covering number of the density zero ideal.

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.

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

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

Wednesday seminar

Prague Set Theory Seminar

6/16/2024 17:21:28

Dear all, The seminar meets on Wednesday June 19th at 11:00 in the Institute of Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building. Program: Katerina Fukova -- Structure of semiartinian rings For (von Neumann) regular semiartinian rings with primitive factors artinian there is an invariant called dimension sequence (Theorem 2.1 in [1]) formed by slices of socle chain of the ring. The necessary conditions on this invariant were studied for example in [2]. We will focus on how much the dimension sequence determines the ring. I will discuss some specific case of commutative rings for which the ring corresponding to any suitable dimension sequence is (up to isomorphism) given by one construction from the ring of eventually constant sequences. Based on the joint work in progress with Jan Trlifaj. [1] P. Růžička, J. Trlifaj, J. Žemlička: Criteria of Steadiness. Marcel Dekker Abelian Groups, Module Theory, and Topology, 1998. [2] J. Žemlička: On socle chains of semiartinian rings with primitive factors artinian. Lobachevskii Journal of Mathematics, Volume 37, 2016, Pages 316-322. Best, David

KGRC talk June 20

Kurt Godel Research Center

6/14/2024 5:55:37

KGRC/Institute of Mathematics invites you to the following talk: Set Theory Seminar Kolingasse 14--16, 1090, 1st floor, SR 10, Thursday, June 20, 11:30am--1:00pm, hybrid mode "Dense ideals (3/3) M. Eskew (U Wien) This is part of a three talk series. The first installment was on June 6 https://ucloud.univie.ac.at/index.php/s/f89ENYQLkdg4BNo, the second one on June 13 https://ucloud.univie.ac.at/index.php/s/HcbKs6J9LrdtKSD. In the third and final lecture of this series, we will finish outlining the proof of the consistency result that all $\aleph_n$ can simultaneously carry dense ideals. This will involve a "uniformization" forcing that follows the Shioya collapse, several strategic closure arguments, and lifting an almost-huge embedding. We will focus on the arguments for getting the result on $\aleph_1$ and $\aleph_2$, and briefly describe how to modify the uniformization forcing to go further. Zoom info: If you have not received the zoom data by the day before the talk, please contact petra.czarnecki@univie.ac.at. Please direct any questions about this talk to vera.fischer@univie.ac.at. * * * * * * * * * Video recordings available so far of the Set Theory Seminar: June 11: L. Notaro (U Turin, IT), "Computable vs. Descriptive Combinatorics of Local Problems" https://ucloud.univie.ac.at/index.php/s/s5D8KKtfrHASKeG June 13: M. Eskew (U Wien), "Dense ideals (2/3)" https://ucloud.univie.ac.at/index.php/s/HcbKs6J9LrdtKSD Video recordings available so far of the Logic Colloquium: June 13: P. Speissegger (McMaster U, Hamilton, CA), "How can model theory help understand Hilbert's 16th problem?" https://ucloud.univie.ac.at/index.php/s/7sdpoGbM3nWFe8o * * * * * * * * * Updates at https://kgrc.univie.ac.at/eventsnews/ -- Institute of Mathematics (Kurt Goedel Research Center, Logic) University of Vienna Kolingasse 14-16, #7.48 1090 Vienna, Austria Phone: +43/ (0)1 4277-50501

56th Nankai Logic Colloquium

Nankai Logic Colloquium

6/12/2024 11:08:33

Hello everyone,

This week our weekly Nankai Logic Colloquium will be in the afternoon.

Our speaker this week will be Lionel Nguyen Van The from Aix-Marseille University. This talk will take place this Friday, June 14th, from 4pm to 5pm (UTC+8, Beijing time).

Title: Ramsey theory in the context of Fraisse classes.

Abstract:
Structural Ramsey theory appeared naturally as a branch of Ramsey theory in the seventies, and is concerned with partition properties of combinatorial objects that are equipped with some structure (typically, in the sense of first order logic). While several seminal results were proved in those years, the subject was offered an unexpected revival thirty years later, whose consequences are still being felt today. This talk will be an attempt to describe the main lines of thought behind this story, starting from the pioneering work of Graham, Leeb, Nesetril, Rödl, Rothschild, Spencer and Voigt, continuing with that of Kechris, Pestov and Todorcevic, and finishing with that of Dobrinen.

________________________________________________________________________________________________

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 56th Nankai Logic Colloquium-- Lionel Nguyen Van The

Time ：16:00pm, Jun. 14, 2024(Beijing Time)

Zoom Number ： 436 658 8683

Passcode ：477893

Link ：https://frontai-hk.zoom.us/j/4366588683?pwd=ob0TsLuLeIl0JT7403RaqvFKgOnuRf.1&omn=86266820140

_____________________________________________________________________

Best wishes,

Ming Xiao

Set theory and topology seminar 11.06.2024 Jadwiga Świerczyńska

Wrocław Set Theory Seminar

6/8/2024 1:15:38

I am happy to announce that at the seminar in set theory and topology (on Tuesday 11.06.2024 at 17:15 in room A.4.1 C-19 (Wrocław University of Science and Technology) the lecture:

"On Q- and selective measures"

will be presented by

Jadwiga Świerczyńska

Abstract:

We will present some generalizations of well-known definitions of types of ultrafilters to the realm of finitely additive measures on $\omega$. We will show a few results similar to the ones for ultrafilters: measure is selective if and only if it is a P-measure and a Q-measure, and that selective measures (Q-measures, respectively) are minimal in the Rudin-Keisler (Rudin-Blass) ordering. We will also show an example of a selective non-atomic measure. The second part will be focused on the integration: we will briefly describe Lebesgue integral with respect to finitely additive measures on $\omega$ and prove that it is a generalization of an ultralimit. Finally, we will present an idea of further generalizations of these definitions for functionals on $\ell^{\infty}$.

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.

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

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

KGRC talks June 11 -13

Kurt Godel Research Center

6/7/2024 5:49:00

KGRC/Institute of Mathematics invites you to the following talks: (updates at https://kgrc.univie.ac.at/eventsnews/ Set Theory Seminar Kolingasse 14--16, 1090, 1st floor, SR 10, Tuesday, June 11, 3:00pm--4:30pm, hybrid mode "Does $\mathsf{DC}$ imply $\mathsf{AC_\omega}$, uniformly?" L. Notaro (U Turin, IT) The axiom of dependent choice $\mathsf{DC}$ and the axiom of countable choice $\mathsf{AC_\omega}$ are two weak forms of the axiom of choice that can be stated for a specific set: $\mathsf{DC}(X)$ assets that any total binary relation on $X$ has an infinite chain; $\mathsf{AC_\omega}(X)$ assets that any countable family of nonempty subsets of $X$ has a choice function. It is well-known that $\mathsf{DC}$ implies $\mathsf{AC_\omega}$. We discuss and sketch the proof of the following theorem: it is consistent with $\mathsf{ZF}$ that there is a set $A\subseteq \mathbb{R}$ such that $\mathsf{DC}(A)$ holds but $\mathsf{AC_\omega}(A)$ fails. This is joint work with Alessandro Andretta. Zoom info: If you have not received the Zoom data by the day before the talk, please contact petra.czarnecki@univie.ac.at Please direct any questions about this talk tovera.fischer@univie.ac.at. * * * * * * * * * Set Theory Seminar Kolingasse 14--16, 1090, 1st floor, SR 10, Thursday, June 13, 11:30am--1:00pm, hybrid mode "Dense ideals (2/3) M. Eskew (U Wien) This is part of a three talk series. The first installment was on June 6 https://kgrc.univie.ac.at/eventsnews/event-details/news/dense-ideals-13/. In the second lecture, we will begin the consistency proof that all $\omega_n$ can carry dense ideals simultaneously. We start with preliminaries on complete $\kappa$-closure, continuous projections, and inverse limits. Then we introduce our main forcing, the Dual Shioya collapse, and establish its key properties. Zoom info: If you have not received the Zoom data by the day before the talk, please contact petra.czarnecki@univie.ac.at Please direct any questions about this talk to vera.fischer@univie.ac.at. * * * * * * * * * Video recordings available so far of the Set Theory Seminar: June 6: M. Eskew (U Wien) "Dense ideals (1/3)" https://ucloud.univie.ac.at/index.php/s/f89ENYQLkdg4BNo -- Institute of Mathematics (Kurt Goedel Research Center, Logic) University of Vienna Kolingasse 14-16, #7.48 1090 Vienna, Austria Phone: +43/ (0)1 4277-50501

55th Nankai Logic Colloquium

Nankai Logic Colloquium

6/5/2024 23:00:24

Hello everyone,

This week our weekly Nankai Logic Colloquium will be in the afternoon.

Our speaker this week will be Rizos Sklinos from the Chinese Academy of Sciences. This talk will take place this Friday, June 7th, from 4pm to 5pm (UTC+8, Beijing time).

Title: First-order sentences in random groups

Abstract: Gromov in his seminal paper introducing hyperbolic groups claimed that a “typical” finitely presented group is hyperbolic. His statement can be made rigorous in various natural ways. The model of randomness that is preferentially focused on is Gromov's density model, as it allows a fair amount of flexibility. In this model a random group is hyperbolic with overwhelming probability. In a different line of thought, Tarski asked whether all non-abelian free groups share the same first-order theory (in the language of groups). This question proved very hard to tackle and only after more than 50 years Sela and Kharlampovich-Myasnikov answered the question positively. Combining the two, J. Knight conjectured that a first-order sentence holds with overwhelming probability in a random group if and only if it is true in a no abelian free group. In joint work with O. Kharlampovich we answer the question positively for universal-existential sentences.

___________________________________________________________________________________________________________________________________________________

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 55th Nankai Logic Colloquium-- Rizos Sklinos

Time ：16:00pm, Jun. 7, 2024(Beijing Time)

Zoom Number ： 436 658 8683

Passcode ：477893

Link ：https://frontai-hk.zoom.us/j/4366588683?pwd=ob0TsLuLeIl0JT7403RaqvFKgOnuRf.1&omn=85231005716

_____________________________________________________________________

Best wishes,

Ming Xiao

Wednesday seminar

Prague Set Theory Seminar

6/5/2024 10:54:02

Dear all, The seminar meets on Wednesday June 12th at 11:00 in the Institute of Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building. Program: Bryant Rosado Silva -- Generically hereditarily equivalent Peano continua We say that a continuum $X$ is hereditarily equivalent if every nondegenerate subcontinuum of it is homeomorphic to X. This concept is one of the main motivations behind the construction of the pseudo-arc. If considered in the hyperspace of continua of X, denoted by Cont(X), it means that Cont(X) \ Fin(X) = { K in Cont(X) : \ K ~ X }. This is an open and dense set, hence comeager, thus we can say that the generic subcontinua of X is homeomorphic to X. Therefore, it is natural to ask if there exist other spaces that satisfy this property of having such collection of homeomorphic sets comeager in the hyperspace. We call these spaces generically hereditarily equivalent continua and show that the generalized Wazewski dendrites W_M for M subset { 3,4,..., infinity } are examples. Moreover, in the hyperspace of maximal order arcs of W_M, the chains having every nondegenerate element homeomorphic to W_M make a comeager subset of the maximal order arcs. Finally, we show that it is possible to find a comeager collection of chains with even more specific properties. This is a joint work with Benjamin Vejnar (Charles University). Best, David

Cross-Alps Logic Seminar (speaker: Lorenz Halbeisen)

Cross-Alps Logic Seminar

6/3/2024 8:23:13

On Friday 07.06.2024 at 16.00 CEST

Lorenz Halbeisen (ETH Zürich)

will give a talk on

The Graph Embedding Property and its relation to the Prime Ideal

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

Wednesday seminar

Prague Set Theory Seminar

6/3/2024 6:14:37

Dear all, No seminar this Wednesday June 5th as many of the regular participants are not available. Best, David

Set theory and topology seminar 4.06.2024 Andres Uribe-Zapata (TU Wien)

Wrocław Set Theory Seminar

6/1/2024 15:49:49

I am happy to announce that at the seminar in set theory and topology (on Tuesday 4.06.2024 at 17:15 in room A.4.1 C-19 (Wrocław University of Science and Technology) the lecture:

"Finitely additive measures on Boolean algebras: freeness and integration"

will be presented by

Andres Uribe-Zapata (TU Wien)

Abstract:

In this talk, we present an integration theory with respect to finitely additive measures on a field of sets $\mathcal{B} \subseteq \mathcal(X)$ for some non-empty set $X$. For this, we start by reviewing some fundamental properties of finitely additive measures on Boolean algebras. Later, we present a definition of the integral in this context and some basic properties of the integral and the integrability. We also study integration over subsets of $X$ to introduce the Jordan algebra and compare the integration on this new algebra with the integration on $\mathcal{B}$. Finally, we say that a finitely additive measure on $\mathcal{B}$ is \emph{free} if $\mathcal{B}$ contains any finite subset of $X$ and its measure is zero. We close the talk by providing some characterizations of free finitely additive measures.

This is a joint work with Miguel A. Cardona and Diego A. Mejía.

References:

[CMU] Miguel A. Cardona, Diego A. Mejía and Andrés F. Uribe-Zapata. Finitely additive measures on Boolean algebras. In Preparation.

[UZ23] Andrés Uribe-Zapata. Iterated forcing with finitely additive measures: applications of probability to forcing theory. Master’s thesis, Universidad Nacional de Colombia, sede Medellín, 2023. https://shorturl.at/sHY59.

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.

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

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

KGRC Talk - June 6

Kurt Godel Research Center

5/31/2024 3:20:30

KGRC/Institute of Mathematics invites you to the following talk: Set Theory Seminar Kolingasse 14--16, 1090, 1st floor, SR 10, Thursday, June 6, 11:30am--1:00pm, hybrid mode "Dense ideals (1/3)" M. Eskew (U Wien) In this three-part lecture series, I will present my recent result with Yair Hayut that it is consistent for all successors of regular cardinals to carry dense ideals. We will start a bit out of order with applications, beginning with Woodin’s "transfer theorem" that shows that if we have diamonds and a normal ideal $J$ on $\kappa^+$ such that $\mathcal{P}(\kappa^+)/J$ is equivalent to $\mathrm{Col}(\kappa$, \kappa^+$), then there is a uniform $\kappa$-complete ideal $K$ on $\kappa^+$ such that $\mathcal{P}(\kappa^+)/K$ is isomorphic to $\mathcal{P}(\kappa)/\mathrm{bounded}$. From this we can derive several combinatorial consequences that address some questions from graph theory and recent work on homological algebra on the ordinals. In the second and third lecture, we will outline the consistency proof. Zoom info: If you have not received the Zoom data by the day before the talk, please contact petra.czarnecki@univie.ac.at Please direct any questions about this talk to vera.fischer@univie.ac.at. * * * * * * * * * May, 23: V. Haberl (TU Wien); "Concentrated sets and γ-sets in the Miller model" https://ucloud.univie.ac.at/index.php/s/7GA9fX7MfSHXYYR Video recordings available so far of the Logic Colloquium: May, 23: P. Szewczak (Cardinal Stefan Wyszyński U, Warsaw, PL); "Centenary of the Menger Conjecture" https://ucloud.univie.ac.at/index.php/s/Zgt6x6sdTpHMq2o * * * * * * * * * Updates at https://kgrc.univie.ac.at/eventsnews/ -- Institute of Mathematics (Kurt Goedel Research Center, Logic) University of Vienna Kolingasse 14-16, #7.48 1090 Vienna, Austria Phone: +43/ (0)1 4277-50501

54th Nankai Logic Colloquium

Nankai Logic Colloquium

5/30/2024 1:23:14

Hello everyone,

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

Our speaker this week will be Andre Nies from the University of Auckland. This talk is going to take place this Friday, May 31, from 4pm to 5pm (UTC+8, Beijing time).

Title: Borel classes of closed subgroups of Sym(N)

Abstract: Closed subgroups of the permutation group Sym(N) are interesting, being the automorphism groups of models M with domain the natural numbers. We study various conjugation-invariant Borel classes from a logician’s point of view. The locally Roelcke precompact groups form the largest class considered. Interesting subclasses include the totally disconnected locally compact (t.d.l.c.) groups, and the oligomorphic group (when M is omega-categorical).

We establish for each class a Borel duality with a class of countable structures that are based on Roelcke precompact open cosets. This is used for an upper bound on the Borel complexity of topological isomorphism relations (with Schlicht and Tent), and for an algorithmic theory in the t.d.l.c. case (with Melnikov).

A lower bound on the complexity of topological isomorphism remains open for the oligomorphic groups. Paolini and Shelah obtained smoothness under the additional hypothesis that each open subgroup has the pointwise stabiliser of a finite set as a subgroup of finite index. Work in progress with Paolini establishes such an upper bound for several other subclasses, such as the case when the model M has no algebraicity.

___________________________________________________________________________________________________________________________________________________

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 54th Nankai Logic Colloquium-- Andre Nies

Time ：16:00pm, May. 31, 2024(Beijing Time)

Zoom Number ： 436 658 8683

Passcode ：477893

Link ：https://frontai-hk.zoom.us/j/4366588683?pwd=ob0TsLuLeIl0JT7403RaqvFKgOnuRf.1&omn=82728819387

_____________________________________________________________________

Best wishes,

Ming Xiao

Cross-Alps Logic Seminar (speaker: Mirna Džamonja)

Cross-Alps Logic Seminar

5/27/2024 14:35:15

On Friday 31.05.2024 at 16.00 CEST

Mirna Džamonja (CNRS-Université de Paris / IHPST)

will give a talk on

Transfer principles in logic

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

Wednesday seminar

Prague Set Theory Seminar

5/27/2024 5:37:28

Dear all, The seminar meets on Wednesday May 29th at 11:00 in the Institute of Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building. Program: Jonathan Cancino Manriquez -- Ultrafilters and large continuum The exact content of the talk has not yet been determined. However, for sure it will involve ultrafilters on the natural numbers, forcing and continuum bigger than omega_2. Best, David

This Week in Logic at CUNY

5/19/2024 22:30:00

This Week in Logic at CUNY:

- - - - Monday, May 20, 2024 - - - -

- - - - Tuesday, May 21, 2024 - - - -

- - - - Wednesday, May 22, 2024 - - - -

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 , The CUNY Graduate Center.

Date and Time: Wednesday May 22, 2024, 7:00 - 8:30 PM. IN PERSON TALK!

Title: Presenting Profunctors.

Abstract: In categorical database theory, profunctors are ubiquitous. For example, they are used to define schemas in the algebraic data model. However, they can also be used to query and migrate data. In this talk, we will discuss an interesting phenomenon that arises when trying to model profunctors in a computer. We will introduce two notions of profunctor presentations: the UnCurried and Curried presentations. They are modeled on thinking of profunctors as functors P: C^op x D -> Set and as functors P: C^op -> Set^D, respectively. Semantically of course, these are equivalent, but their syntactic properties are quite different. The UnCurried presentations are more intuitive and easier to work with, but they carry a fatal flaw: there does not exist a semantics-preserving composition operation of UnCurried presentations that also preserves finiteness. Therefore we introduce the Curried presentations and show that they remedy this flaw. In the process, we characterize which UnCurried Presentations can be made Curried, and discuss some applications. This talk will be based off of this recent preprint which is joint work with Gabriel Goren Roig and Joshua Meyers.

- - - - Thursday, May 23, 2024 - - - -

- - - - Friday, May 24, 2024 - - - -

Next Week in Logic at CUNY:

- - - - Monday, May 27, 2024 - - - -

- - - - Tuesday, May 28, 2024 - - - -

- - - - Wednesday, May 29, 2024 - - - -

- - - - Thursday, May 30, 2024 - - - -

- - - - Friday, May 31, 2024 - - - -

- - - - 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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KGRC Talks - May 24

Kurt Godel Research Center

5/17/2024 4:16:21

KGRC/Institute of Mathematics invites you to the following talks: Set Theory Seminar Kolingasse 14--16, 1090, 1st floor, SR 10, Thursday, May 23, 11:30am--1:00pm, hybrid mode "Concentrated sets and $\gamma$-sets in the Miller model" V. Haberl (TU Wien) Bartoszyński and Halbeisen conjectured that in the Miller model there exists a concentrated set of reals of size $\mathfrak{c} = \omega_2$. Let us recall that a set $X\subseteq 2^\omega$ is concentrated if there exists a countable $Q\subseteq X$ such that $|X\setminus U|\leq \omega$ for every open set $U \subseteq 2^\omega$ with $Q\subseteq U$. In our talk we shall present the main ideas of the proof that this conjecture is false. Concentrated sets are canonical examples of Rothberger spaces of reals. We want to analyse the possible cardinalities of sets of reals satisfying selection principles in the Miller model. To avoid triviality we are interested in the totally imperfect cases, i.e. spaces that do not contain a copy of the Cantor space. Note that since $\mathfrak{d}$-concentrated sets are totally imperfect Menger spaces, there are such spaces of size continuum (since $\mathfrak{d} = \mathfrak{c}$). We shall sketch the proof that for the strongest selection principle, the $\gamma$-set property, only cardinality atmost $\omega_1$ is possible. We hope that the tools of our results can be used as a prototype for the non-existence of Rothberger sets of reals with cardinality $\mathfrak{c}$. The goal would be to prove the same for Hurewicz totally imperfect sets of reals, the latter being a weaker property than Rothberger in the Miller model. The talk will be based on a recent joint work with Piotr Szewczak and Lyubomyr Zdomskyy. Zoom info: If you have not received the Zoom data by the day before the talk, please contact petra.czarnecki@univie.ac.at. Please direct any questions about this talk to vera.fischer@univie.ac.at. * * * * * * * * * Logic Colloquium Oskar-Morgenstern-Platz 1, 1090, 2nd floor, HS 11, Thursday, May 23, 3:00pm--3:50pm, hybrid mode "Centenary of the Menger Conjecture" P. Szewczak (Cardinal Stefan Wyszyński University, Warsaw, PL) In 1924, Menger observed that any metric space $X$ which is \emph{$\sigma$-compact} (i.e., it is a countable union of its compact subsets) has such a property that for any basis $\mathcal{B}$ of $X$, there are sets $B_0,B_1,\ldots\in\mathcal{B}$, such that $\mathrm{lim}_{n\to\infty}\mathrm{diam}(B_n)=0$ and $X=\bigcup_{n\in \omega }B_n$. Menger conjectured that the above property characterizes $\sigma$-compactness in the class of metric spaces. Soon thereafter Hurewicz reformulated the Menger property without using a metric: for any sequence $\mathcal{U}_0,\mathcal{U}_1,\ldots$ of open covers of a given topological space, there are finite sets $\mathcal{F}_1\subseteq\mathcal{U}_0, \mathcal{F}_1\subseteq\mathcal{U}_1,\ldots$ such that the family $\bigcup_{n\in\omega}\mathcal{F}_n$ is an open cover of the space.In that way, the definition of the Menger property was extended on all topological spaces. By the results of Fremlin--Miller and Bartoszyński--Tsaban, there is in ZFC a subspace of the real line which is Menger but no $\sigma$-compact. The aim of the talk is to present an overview of the Menger property which is one of the most influential property in the topological selections theory and it has many connections to topology, set-theory and function spaces. Zoom info: If you have not received the Zoom data by the day before the talk, please contact petra.czarnecki@univie.ac.at. Please direct any questions about this talk to matthias.aschenbrenner@univie.ac.at. * * * * * * * * * Video recordings available so far of the Set Theory Seminar: May, 14: O. Zindulka (Czech Technical U, Prague, CZ) "Combinatorics of Uniform Covers" https://ucloud.univie.ac.at/index.php/s/2BBqLQZy7TownbM May, 16: C.B. Switzer (U Wien) "Baumgartner's Axiom and Cardinal Characteristics: A Sparse Look at Dense Sets of Reals III" https://ucloud.univie.ac.at/index.php/s/BtQZfJS54fSnTJM Video recordings available so far of the Logic Colloquium: May, 16: R. Sklinos (Chinese Academy of Sciences, Beijing, CN) "First-order sentences in random groups" https://ucloud.univie.ac.at/index.php/s/59BbzjWPdGiCB8x * * * * * * * * * Updates at https://kgrc.univie.ac.at/eventsnews/. -- Institute of Mathematics (Kurt Goedel Research Center, Logic) University of Vienna Kolingasse 14-16, #7.48 1090 Vienna, Austria Phone: +43/ (0)1 4277-50501

Wednesday seminar

Prague Set Theory Seminar

5/16/2024 4:21:35

Dear all, The seminar meets on Wednesday May 22nd at 11:00 in the Institute of Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building. Next week there will also be an extra session of the Set Theory and Analysis seminar on Friday May 24th at 14:00, talk delivered by John Truss. (As well as an interesting talk on Tuesday morning.) See here: https://www.math.cas.cz/index.php/events/seminar/6 Program (Wednesday): Jindřich Zapletal -- Partition properties of omega one without choice I will show that certain natural partition properties of omega one which follow from the axiom of determinacy still hold in balanced extensions of the Solovay model, making them consistent with such objects as Vitali sets or ultrafilters. Best, David

53rd Nankai Logic Colloquium

Nankai Logic Colloquium

5/16/2024 0:21:51

Hello everyone,

This week our weekly Nankai Logic Colloquium is going to be in the afternoon, but at an irregular time, as we have two speakers this week.

Our speakers this week will be Yang Zheng and Ruiwen Li, both from Nankai University. This talk is going to take place this Friday, May 17th, from 2:30 pm to 5 pm (UTC+8, Beijing time). The first talk is starting at 2:30pm, and the second talk is starting at 4pm. Both talks are offline/online hybrid.

Yang Zheng:

Title: On equivalence relations induced by Polish groups

Abstract: In this talk, we introduce Borel orbit equivalence relations, denoted by E(G), which can well-describe the structures and properties of a Polish group G from the perspective of Borel reduction.

Given a Polish group G, let E(G) be the right coset equivalence relation $G^\omega/c(G)$, where c(G) is the group of all convergent sequences in G. We shall present the following results: for a non-trivial Polish group G, we have that: (1) G is a countable group iff $E(G)\sim_B E_0$; (2) G is TSI non-archimedean uncountable iff $E(G)\sim_B E^\omega_0$; and (3) G is non-archimedean iff $E(G)\leq_B =^+$. In particular, $E(S_\infty)\sim_B =^+$ holds. Moreover, we will provide some Rigid Theorems and a Pre-rigid Theorem on TSI Polish groups, which can transform the existence problem of Borel reduction between E(G) equivalence relations, into the existence problem of well-behaved continuous homomorphisms between Polish groups. This is a joint work with Longyun Ding.

Ruiwen Li:

Title: Topological Type and Conjugacy Relation on Minimal Systems

Abstract: The complexity of conjugacy relation on minimal systems under Borel reducibility is a well-known question in descriptive set theory. In this talk, by analyzing the conjugacy relation on Oxtoby systems, I'll define an equivalence relation named topological type, this relation gives a lower bound of conjugacy complexity of minimal systems and shows that the conjugacy relation on minimal systems cannot be classified by countable structures. Moreover, when considering the isomorphism relation of pointed minimal systems, the topological type relation describes its exact complexity.

__________________________________________________________________________________________________________________________

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

Title ：The 53th Nankai Logic Colloquium

Time ：14:30pm, May. 17, 2024(Beijing Time)

Zoom Number ： 371 037 9317

Passcode ：477893

Link ：https://zoom.us/j/3710379317?pwd=WEpLTjBtV1B2SHZaaFpnWU1qNzJVQT09&omn=92298090494

_____________________________________________________________________

The records of past talks can be accessed at https://space.bilibili.com/253421893.

Best wishes,

Ming Xiao

UPDATE: This Week in Logic at CUNY

This Week in Logic at CUNY

5/13/2024 10:25:31

Hi everyone,

Note the addition of two talks in the NYC Category Theory Seminar, May 15 and May 22.

Best,

Jonas

This Week in Logic at CUNY:

- - - - Monday, May 13, 2024 - - - -

- - - - Tuesday, May 14, 2024 - - - -

Computational Logic Seminar

Spring 2024 (online)
Tuesday, May 14, Time 2:00 - 4:00 PM (EDT)
zoom link: ask Sergei Artemov sartemov@gmail.com

Speaker: Hans van Ditmarsch, CNRS, IRIT, University of Toulouse, France

Title: Epistemic logic and simplicial complexes

Abstract: All my working life as a logician epistemic logic came with Kripke models, in particular the kind for multiple agents with equivalence relations to interpret knowledge. Sure enough, I knew about enriched Kripke models, like subset spaces, or with topologies. But at some level of abstraction you get back your standard Kripke model. Imagine my surprise, around 2018, that there is an entirely dual sort of structure on which the epistemic logical language can be interpreted and that results in the same S5 logic: simplicial complexes. Instead of points that are worlds and links labeled with agents, we now have points that are agents and links labeled with worlds. Or, instead of edges (links), triangles, tetrahedrons, etcetera, that represent worlds. Simplicial complexes are well-known within combinatorial topology and have wide usage in distributed systems to model (a)synchronous computation. The link with epistemic modal logic is recent, spreading out from Mexico City and Paris to other parts of the world, like Vienna and Bern. Other logics are relevant too, for example KB4, in order to encode crashed processes/agents. Other epistemics are relevant too, and in particular distributed knowledge, which facilitates further generalizations from simplicial complexes to simplicial sets. It will be my pleasure to present my infatuation with this novel development connecting epistemic logic and distributed computing. Suggested introductory reading is:

https://arxiv.org/abs/2002.08863
https://link.springer.com/chapter/10.1007/978-3-030-75267-5_1
Knowledge and Simplicial Complexes
Hans van Ditmarsch, Eric Goubault, Jeremy Ledent, Sergio Rajsbaum

https://drops.dagstuhl.de/entities/document/10.4230/DagRep.13.7.34
Epistemic and Topological Reasoning in Distributed Systems (Dagstuhl Seminar 23272)
Armando Castañeda, Hans van Ditmarsch, Roman Kuznets, Yoram Moses, Ulrich Schmid
Section 4.3 Representing Epistemic Attitudes via Simplicial Complexes

- - - - Wednesday, May 15, 2024 - - - -

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: Raymond Puzio.

Date and Time: Wednesday May 15, 2024, 7:00 - 8:30 PM. IN-PERSON!

Title: Uniqueness of Classical Retrodiction.

Abstract: In previous talks at this Category seminar and at the Topology, Geometry and Physics seminar, Arthur Parzygnat showed how Bayesian inversion and its generalization to quantum mechanics may be interpreted as a functor on a suitable category of states which satisfies certain axioms. Such a functor is called a retrodiction and Parzygnat and collaborators conjectured that retrodiction is unique. In this talk, I will present a proof of this conjecture for the special case of classical probability theory on finite state spaces.

In this special case, the category in question has non-degenerate probability distributions on finite sets as its objects and stochastic matrices as its morphisms. After preliminary definitions and lemmas, the proof proceeds in three main steps.

In the first step, we focus on certain groups of automorphisms of certain objects. As a consequence of the axioms, it follows that these groups are preserved under any retrodiction functor and that the restriction of the functor to such a group is a certain kind of group automorphism. Since this group is isomorphic to a Lie group, it is easy to prove that the restriction of a retrodiction to such a group must equal Bayesian inversion if we assume continuity. If we do not make that assumption, we need to work harder and derive continuity "from scratch" starting from the positivity condition in the definition of stochastic matrix.

In the second step, we broaden our attention to the full automorphism groups of objects of our category corresponding to uniform distributions. We show that these groups are generated by the union of the subgroup consisting of permutation matrices and the subgroup considered in the first step. From this fact, it follows that the restriction of a retrodiction to this larger group must equal Bayesian inversion.

In the third step, we finally consider all the objects and morphisms of our category. As a consequence of what we have shown in the first two steps and some preliminary lemmas, it follows that retrodiction is given by matrix conjugation. Furthermore, Bayesian inversion is the special case where the conjugating matrices are diagonal matrices. Because the hom sets of our category are convex polytopes and a retrodiction functor is a continuous bijection of such sets, a retodiction must map polytope faces to faces. By an algebraic argument, this fact implies that the conjugating matrices are diagonal, answering the conjecture in the affirmative.

Paper.

- - - - Thursday, May 16, 2024 - - - -

*** FINAL EXAMS WEEK BEGINS - CUNY GRADUATE CENTER ***

- - - - Friday, May 17, 2024 - - - -

Next Week in Logic at CUNY:

- - - - Monday, May 20, 2024 - - - -

- - - - Tuesday, May 21, 2024 - - - -

- - - - Wednesday, May 22, 2024 - - - -

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 , The CUNY Graduate Center.

Date and Time: Wednesday May 22, 2024, 7:00 - 8:30 PM. IN PERSON TALK!

Title: Presenting Profunctors.

Abstract: In categorical database theory, profunctors are ubiquitous. For example, they are used to define schemas in the algebraic data model. However, they can also be used to query and migrate data. In this talk, we will discuss an interesting phenomenon that arises when trying to model profunctors in a computer. We will introduce two notions of profunctor presentations: the UnCurried and Curried presentations. They are modeled on thinking of profunctors as functors P: C^op x D -> Set and as functors P: C^op -> Set^D, respectively. Semantically of course, these are equivalent, but their syntactic properties are quite different. The UnCurried presentations are more intuitive and easier to work with, but they carry a fatal flaw: there does not exist a semantics-preserving composition operation of UnCurried presentations that also preserves finiteness. Therefore we introduce the Curried presentations and show that they remedy this flaw. In the process, we characterize which UnCurried Presentations can be made Curried, and discuss some applications. This talk will be based off of this recent preprint which is joint work with Gabriel Goren Roig and Joshua Meyers.

- - - - Thursday, May 23, 2024 - - - -

- - - - Friday, May 24, 2024 - - - -

- - - - 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.

This Week in Logic at CUNY

5/12/2024 22:31:00

Hi everyone,

This will be our last edition of "This Week in Logic at CUNY" for the Spring 2024 semester -- regular mailings will resume in late August. Special updates may be sent for events that arise in the meantime.

Wishing you a happy and productive summer!

All the best,

Jonas

This Week in Logic at CUNY:

- - - - Monday, May 13, 2024 - - - -

- - - - Tuesday, May 14, 2024 - - - -

Computational Logic Seminar

Spring 2024 (online)
Tuesday, May 14, Time 2:00 - 4:00 PM (EDT)
zoom link: ask Sergei Artemov sartemov@gmail.com

Speaker: Hans van Ditmarsch, CNRS, IRIT, University of Toulouse, France

Title: Epistemic logic and simplicial complexes

Abstract: All my working life as a logician epistemic logic came with Kripke models, in particular the kind for multiple agents with equivalence relations to interpret knowledge. Sure enough, I knew about enriched Kripke models, like subset spaces, or with topologies. But at some level of abstraction you get back your standard Kripke model. Imagine my surprise, around 2018, that there is an entirely dual sort of structure on which the epistemic logical language can be interpreted and that results in the same S5 logic: simplicial complexes. Instead of points that are worlds and links labeled with agents, we now have points that are agents and links labeled with worlds. Or, instead of edges (links), triangles, tetrahedrons, etcetera, that represent worlds. Simplicial complexes are well-known within combinatorial topology and have wide usage in distributed systems to model (a)synchronous computation. The link with epistemic modal logic is recent, spreading out from Mexico City and Paris to other parts of the world, like Vienna and Bern. Other logics are relevant too, for example KB4, in order to encode crashed processes/agents. Other epistemics are relevant too, and in particular distributed knowledge, which facilitates further generalizations from simplicial complexes to simplicial sets. It will be my pleasure to present my infatuation with this novel development connecting epistemic logic and distributed computing. Suggested introductory reading is:

https://arxiv.org/abs/2002.08863
https://link.springer.com/chapter/10.1007/978-3-030-75267-5_1
Knowledge and Simplicial Complexes
Hans van Ditmarsch, Eric Goubault, Jeremy Ledent, Sergio Rajsbaum

https://drops.dagstuhl.de/entities/document/10.4230/DagRep.13.7.34
Epistemic and Topological Reasoning in Distributed Systems (Dagstuhl Seminar 23272)
Armando Castañeda, Hans van Ditmarsch, Roman Kuznets, Yoram Moses, Ulrich Schmid
Section 4.3 Representing Epistemic Attitudes via Simplicial Complexes

- - - - Wednesday, May 15, 2024 - - - -

- - - - Thursday, May 16, 2024 - - - -

*** FINAL EXAMS WEEK BEGINS - CUNY GRADUATE CENTER ***

- - - - Friday, May 17, 2024 - - - -

Next Week in Logic at CUNY:

- - - - Monday, May 20, 2024 - - - -

- - - - Tuesday, May 21, 2024 - - - -

- - - - Wednesday, May 22, 2024 - - - -

- - - - Thursday, May 23, 2024 - - - -

- - - - Friday, May 24, 2024 - - - -

- - - - 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.

120 Years of Choice, Leeds, 8–12 July 2024

Conference

5/12/2024 1:00:00

120 Years of Choice, 8–12 July, 2024 This is a reminder for our conference 120 Years of Choice that will take place at the University of Leeds from 8th to 12th of July. For those that are still undecided, the scope of the conference is not limited to the Axiom of Choice and we will have a wide variety of speakers coming from different areas. The same of course also applies to poster submissions. Registration is still open until June 20th (20/06/2024), but we would like to ask all participants to register at their earliest convenience, so that we can plan accordingly. We have now extended the submission deadline for posters to May 31st (31/05/2024). Let us reiterate that we may be able to offer some financial support to those presenting a poster. We encourage any early career researchers to apply. For registration see more details at https://120ac.set-theory.info or email us at 120ac@leeds.ac.uk.

Link to more info

Tagged: Assaf Rinot, Assaf Shani, Azul Fatalini, David Asperó, Diana Montoya, Inbar Oren, John Steel, Kameryn WilliamsLorenzo Notaro, Martina Iannella, Moti Gitik, Natasha Dobrinen, Sheila Miller Edwards, Siiri Kivimäki, Toshimichi Usuba, Yair Hayut, Philipp Schlicht

Set Theory in the United Kingdom, Oxford, 16 May 2024

Conference

5/12/2024 0:00:00

STUK 13 ("Set Theory in the United Kingdom") will take place at the Mathematical Institute of the University of Oxford on Thursday, 16 May 2024. We have already secured István Juhász and Thilo Weinert as invited speakers who both plan to be there in person. https://www.dpmms.cam.ac.uk/~dbl25/STUK/ The schedule will be roughly as for the past meetings: we start in the late morning, have one talk before lunch, then lunch, then two more talks, and then ample time for "informal presentations" where everyone can and should speak to present themselves, their open questions, their research project, or their results.

Link to more info

Tagged: István Juhász, Julia Millhouse, Thilo Weinert

Wednesday seminar

Prague Set Theory Seminar

5/11/2024 3:07:29

Dear all, The seminar meets on Wednesday May 15th at 11:00 in the Institute of Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building. Program: Jonathan Cancino Manriquez -- Basically generated ultrafilters This is a continuation of the last talk. We will recall and extend some facts that were already presented. Then we will prove some results on the existence of basically generated ultrafilters. Best, David

KGRC Set Theory Talks - May 12-17

Kurt Godel Research Center

5/8/2024 12:17:52

KGRC/Institute of Mathematics invites you to the following talks: SetTheory Seminar Kolingasse 14–16, 1090, 1st floor, SR 10, hybrid mode TUESDAY, May 14, 3:00pm–4:30pm ”Combinatorics of Uniform Covers” O. Zindulka (Czech Technological University, Prague, CZ) We look at diagonalization properties for sequences of various flavors of uniform covers of separable metric spaces and we describe them with game-theoretic and Ramsey-like partition properties. Applications include strong measure zero, null-additive and meager-additive sets in Polish groups, Menger-bounded spaces etc. Some highlights: a link to fractal measures and how it can help with calculation of cardinal invariants; Galvin-Mycielski-Solovay Theorem in various contexts;a solution to a Scheepers problem regarding products of strong measure zero spaces. Zoom info: If you have not received the Zoom data by the day before the talk, please contact petra.czarnecki@univie.ac.at Please direct any questions about this talk to vera.fischer@univie.ac.at. * * * * * * * * * Set Theory Seminar Kolingasse 14--16, 1090, 1st floor, SR 10, Thursday, May 16, 11:30am--1:00pm, hybrid mode "Baumgartner's Axiom and Cardinal Characteristics: A Sparse Look at Dense Sets of Reals III" C. B. Switzer (U Wien) Mini-course (25.04.2024-16.05.2024, 3 lectures) - 3rd lecture: Given a cardinal $\kappa$, a set of reals $A\subseteq \mathbb R$ is $\kappa$-dense if its intersection with any open interval has size $\kappa$. Baumgartner's axiom (BA)---proved consistent by Baumgartner in 1973---states that all $\aleph_1$-dense sets of reals are order isomorphic with the induced linear order from $\mathbb R$. This is the most straightforward generalization to the uncountable of Cantor's proof that all countable dense linear orders without endpoints are order isomorphic. BA has variations to other topological spaces---given a topological space $X$, a subset $A \subseteq X$ is $\kappa$-dense if its intersection with each non-empty open subset has size $\kappa$. The axiom BA($X$) states that given any two $\aleph_1$-dense subsets of $X$, say $A$ and $B$, there is an autohomeomorphism of $X$ mapping $A$ onto $B$. In this parlance BA is equivalent to BA ($\mathbb R$). Surprisingly BA is not equivalent to BA ($\mathbb R^n$) for any finite $1< n < \omega$. In fact BA does not follow from Martin's Axiom (Abraham-Rubin-Shelah) though BA($\mathbb R^n$) does (in fact from $\mathfrak{p} > \aleph_1$) for each $n > 1$ (Steprāns-Watson). In these three lectures I will discuss these ideas and some related ones including the question of when BA($X$) implies BA($Y$) for Polish spaces $X$ and $Y$. Central to these questions are the role of cardinal characteristics including the celebrated theorem of Todorčević that BA implies $\mathfrak b > \aleph_1$ as well as a recent, higher dimensional analogue of this result that for any $n < \omega$ BA($\mathbb R^n$) implies $\mathfrak b > \aleph_1$ (S.-Steprāns). There are many beautiful open problems in this area and I plan to make discussing them a focal point of the talks. The talks will start slowly and should be accessible to students. Time permitting, the final talk will include some new results. If and when these results are presented, they are joint work with Juris Steprāns. Zoom info: If you have not received the Zoom data by the day before the talk, please contact petra.czarnecki@univie.ac.at Please direct any questions about this talk to vera.fischer@univie.ac.at. * * * * * * * * * Video recordings available of the Set Theory Workshop ”Compactness and Cardinal Invariants, Vienna, May 3, 2024: C. Agostini (TU Wien), "On Nagata-Smirnov spaces and metrizability-like properties" https://ucloud.univie.ac.at/index.php/s/DpQiNFzdqxpptfT S. Bardyla (U Wien), "Bohr compactification of discrete groups and Schur ultrafilters" https://ucloud.univie.ac.at/index.php/s/3cpFpjNMZ6z5ejG J. Cancino (Czech Academy of Sciences, Prague, CZ), "Some results on Tukey types of ultrafilters on the natural numbers" https://ucloud.univie.ac.at/index.php/s/8eiGqEsGCszYEG6 M. Iannella (TU Wien), "Descriptive consequences of rank-into-rank axioms" https://ucloud.univie.ac.at/index.php/s/rSjEQYjTzbdE6os Ch. Lambie-Hanson (Czech Academy of Sciences, Prague, CZ), "Hajnal-Máté graphs and club guessing" https://ucloud.univie.ac.at/index.php/s/pzpofnbPMyJZ9WY A. Medini (TU Wien), "A complete classification of the zero-dimensional homogeneous spaces under determinacy" https://ucloud.univie.ac.at/index.php/s/QfZ8ccqaKk5anwH J.M. Millhouse (U Wien), "Projectively definable mad families of multiple sizes" https://ucloud.univie.ac.at/index.php/s/kGPsfCgqJBQPKPk Š. Stejskalová (Charles U, Prague, CZ), "Forcing over a free Suslin tree" https://ucloud.univie.ac.at/index.php/s/HTpXbwd9cd5zcRJ C.B. Switzer (U Wien), "Baumgartner’s axiom and its higher dimensional versions" https://ucloud.univie.ac.at/index.php/s/224KHG2b9nJgp3w T. van der Vlugt (TU Wien), "The horizontal direction" https://ucloud.univie.ac.at/index.php/s/nSGmaJNbzpoHAoN * * * * * * * * * Updates at https://kgrc.univie.ac.at/eventsnews/) -- Institute of Mathematics (Kurt Goedel Research Center, Logic) University of Vienna Kolingasse 14-16, #7.48 1090 Vienna, Austria Phone: +43/ (0)1 4277-50501

This Week in Logic at CUNY

5/5/2024 22:07:18

This Week in Logic at CUNY:

- - - - Monday, May 6, 2024 - - - -

Logic and Metaphysics Workshop
Date: Monday, May 6, 4.15-6.15pm (NY time)
Room: Graduate Center Room 7395

Lorenzo Rossi (Turin)
Title: Alethic pluralism and Kripkean truth

Abstract: According to alethic pluralism, there is more than one way of being true: truth is not unique, in that there is a plurality of truth properties each of which pertains to a specific domain of discourse. This paper shows how such a plurality can be represented in a coherent formal framework by means of a Kripke-style construction that yields intuitively correct extensions for distinct truth predicates. The theory of truth it develops can handle at least three crucial problems that have been raised in connection with alethic pluralism: mixed compounds, mixed inferences, and semantic paradoxes.

Note: This is joint work with Andrea Iacona (Turin) and Stefano Romeo (Turin).

- - - - Tuesday, May 7, 2024 - - - -

MOPA (Models of Peano Arithmetic)
CUNY Graduate Center
Virtual (email Victoria Gitman (vgitman@gmail.com) for meeting id)

Tuesday, May 7, 1pm

Ali Enayat, University of Gothenburg
Tarski's undefinability of truth theorem strikes again

Tarski's undefinability of truth theorem has two versions, the first one deals with truth itself, takes some effort to prove, and is a descendant of the Epimenides (liar) paradox. The second one deals with the related concept of satisfaction, has a one-line proof, and is a descendent of Russell's paradox. This talk is about the first one, which appeared in the 1953 monograph 'Undecidable Theories' by Tarski, Mostowski, and Robinson; it was employed there to show the essential undecidability of consistent theories that can represent all recursive functions (a strong form of the Gödel-Rosser incompleteness theorem). I will present Tarski's original 1953 formulation (which differs from the common formulation in modern expositions) and will explain how it was used in my recent work with Albert Visser to show that no consistent completion of a sequential theory whose signature is finite is axiomatizable by a collection of sentences of bounded quantifier-alternation-depth. A variant of this result was proved independently by Emil Jeřábek, as I will explain. Our proof method has a pedagogical dividend since it allows one to replace the cryptic Gödel-Carnap fixed point lemma with the perspicuous undefinability of truth theorem in the proof of the Gödel-Rosser incompleteness theorem.

Computational Logic Seminar

Spring 2024 (online)
Tuesday, May 7, Time 2:00 - 4:00 PM (EDT)
zoom link: ask Sergei Artemov sartemov@gmail.com
Speaker: SREEHARI KALLOORMANA, Graduate Center CUNY
Title: Formal Argumentation Theory and Argumentation Logics.

Abstract: Deductive Logic is monotonic, in that when the set of premises grows, the set of conclusions grows as well. Since the 1980s, Non-monotonic Logics, where this does not hold, have been studied to model commonsense reasoning, especially in the field of artificial intelligence. In this talk, we will be looking at argument-based nonmonotonic logics, which formalize the notion of attack and defeat in the field of argumentation theory. We will consider briefly abstract argumentation frameworks and the various semantic notions proposed by P.M. Dung in 1995, followed by logic-based structured argumentation frameworks `a la John Pollock, and the more recent ASPIC framework. Various notions of argument attack/defeat fundamental to argumentation, such as rebuttal, undercutting, and undermining, will be discussed. We will then introduce and discuss the idea of reasoning about argumentation using Justification logic, by introducing priority orderings over formulas and justification terms.

- - - - Wednesday, May 8, 2024 - - - -

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: Juan Orendain, Case Western Univeristy.

Date and Time: Wednesday May 8, 2024, 7:00 - 8:30 PM. ZOOM TALK.

Title: Canonical squares in fully faithful and absolutely dense equipments.

Abstract: Equipments are categorical structures of dimension 2 having two separate types of 1-arrows -vertical and horizontal- and supporting restriction and extension of horizontal arrows along vertical ones. Equipments were defined by Wood in [W] as 2-functors satisfying certain conditions, but can also be understood as double categories satisfying a fibrancy condition as in [Sh]. In the zoo of 2-dimensional categorical structures, equipments nicely fit in between 2-categories and double categories, and are generally considered as the 2-dimensional categorical structures where synthetic category theory is done, and in some cases, where monoidal bicategories are more naturally defined.

In a previous talk in the seminar, I discussed the problem of lifting a 2-category into a double category along a given category of vertical arrows, and how this problem allows us to define a notion of length on double categories. The length of a double category is a number that roughly measures the amount of work one needs to do to reconstruct the double category from a bicategory along its set of vertical arrows.

In this talk I will review the length of double categories, and I will discuss two recent developments in the theory: In the paper [OM] a method for constructing different double categories from a given bicategory is presented. I will explain how this construction works. One of the main ingredients of the construction are so-called canonical squares. In the preprint [O] it is proven that in certain classes of equipments -fully faithful and absolutely dense- every square that can be canonical is indeed canonical. I will explain how from this, it can be concluded that fully faithful and absolutely dense equipments are of length 1, and so they can be 'easily' reconstructed from their horizontal bicategories.

References:
[O] Length of fully faithful framed bicategories. arXiv:2402.16296.
[OM] J. Orendain, R. Maldonado-Herrera, Internalizations of decorated bicategories via π-indexings. To appear in Applied Categorical Structures. arXiv:2310.18673.
[W] R. K. Wood, Abstract Proarrows I, Cahiers de topologie et géométrie différentielle 23 3 (1982) 279-290.
[Sh] M. Shulman, Framed bicategories and monoidal fibrations. Theory and Applications of Categories, Vol. 20, No. 18, 2008, pp. 650–738.

- - - - Thursday, May 9, 2024 - - - -

- - - - Friday, May 10, 2024 - - - -

Model Theory Seminar
CUNY Graduate Center
Friday May 10, 12:30pm NY time, Room: 6495

Alf Dolich, CUNY
The decidability of the rings Z/mZ

In this expository talk I will discuss recent work of Derakhshan and Macintyre on the decidability of the common theory of the rings Z/mZ as m varies through the natural numbers m>1.

Logic Workshop
CUNY Graduate Center
Friday May 10, 2:00pm-3:30pm, Room 5417

Roman Kossak, CUNY
The lattice problem for models of arithmetic

The lattice problem for models of PA is to determine which lattices can be represented either as lattices of elementary substructures of a model of PA or, more generally, which can be represented as lattices of elementary substructures of a model N that contain a given elementary substructure M of N.

Since the 1970's, the problem generated much research with highly nontrivial results with proofs combining specific methods in the model theory of arithmetic with lattice theory and various combinatorial theorems. The problem has a definite answer in the case of distributive lattices, and, despite much effort, there are still many open questions in the nondistributive case. I will briefly survey some early results and present a few proofs that illustrate the difference between the distributive and nondistributive cases.

Next Week in Logic at CUNY:

- - - - Monday, May 13, 2024 - - - -

- - - - Tuesday, May 14, 2024 - - - -

- - - - Wednesday, May 15, 2024 - - - -

- - - - Thursday, May 16, 2024 - - - -

*** FINAL EXAMS WEEK BEGINS - CUNY GRADUATE CENTER ***

- - - - Friday, May 17, 2024 - - - -

- - - - 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.

Logic Seminar 8 May 2024 17:00 hrs at NUS

NUS Logic Seminar

5/3/2024 2:34:26

Invitation to the Logic Seminar at the National University of Singapore Date: Wednesday, 08 May 2024, 17:00 hrs Place: NUS, Department of Mathematics, S17#04-04 Speaker: Vittorio Cipriano Title: Characterizing different notions of learnability of structures URL: http://www.comp.nus.edu.sg/~fstephan/logicseminar.html In this talk, we combine computable structure theory and inductive inference to study learning of families of structures. All the structures we consider are relational and countable and all the families of structures we consider are at most countable. The framework we use was defined in a series of papers by Bazhenov, Fokina, Koetzing and San Mauro. In a nutshell, the framework models the scenario in which, given a family of structures K, a learner receives more and more information about the atomic diagram of a copy of some A in K and, at each stage, is required to output a conjecture about the isomorphism type of such a structure. In this context, a natural criterion to consider is Ex-learning in which we require the learner to stabilize to the correct conjecture after finitely many steps. Together with Bazhenov and San Mauro we gave a descriptive set-theoretic characterization of Ex-learning. Namely, we showed that a family of structures is Ex-learnable if and only if the corresponding isomorphism problem continuously reduces to E_0, the equivalence relation of eventual agreement on infinite binary sequences. Replacing E_0 with other equivalence relations, one obtains a hierarchy to rank such isomorphism problems. That is, a family of structures K is E-learnable, for an equivalence relation E, if there is a continuous reduction from the isomorphism problem associated with K to E. We aim to obtain model-theoretic characterization of E-learning for different equivalence relations E. Some characterizations are already present in the literature: here we show that a family of structures K such that for any A_i, A_j in K there is a Sigma_n^{inf} formula satisfied by A_i but not by A_j is E-learnable if and only if E is the (iteration of the) Friedman-Stanely jump of the identity either on natural numbers or on Cantor space. We also show that other learning criteria coming from the classical setting of inductive inference of formal languages or recursive functions have a nice model-theoretic characterization. This talk collects joint works with Bazhenov, Jain, Marcone, San Mauro and Stephan.

Fwd: 9 FMP: przestrzenie Banacha: geometria i operatory

Wrocław Set Theory Seminar

5/1/2024 3:26:46

---------- Forwarded message ---------
Od: Grzegorz Plebanek <grzegorz.plebanek@math.uni.wroc.pl>
Date: wt., 30 kwi 2024 o 22:47
Subject: Fwd: 9 FMP: przestrzenie Banacha: geometria i operatory
To: Szymon Żeberski <szymon.zeberski@pwr.edu.pl>
Cc: <sebastian.jachimek@math.uni.wroc.pl>, Piotr Borodulin-Nadzieja <pborod@math.uni.wroc.pl>

Szymonie, rozeslij to, proszę do wszystkich z seminarium. To Jest wiadomość od Tomka Kanii (który prosi o informowanie wszystkich zainteresowanych) w sprawie sesji Przestrzenie Banacha, ale na liście konferencji jest też sesja Teoria Mnogości. Pozdrawiam, G

---------- Forwarded message ---------
Od: Tomasz Kania <tomasz2.kania@uj.edu.pl>
Date: wt., 30 kwi 2024 o 21:10
Subject: 9 FMP: przestrzenie Banacha: geometria i operatory

okazuje się, że sesja z przestrzeni Banacha się odbędzie (nie jest jednak jeszcze jasne, którego dnia konferencji); jeżeli nadal wyrażasz zainteresowanie przyjazdem, bardzo proszę o przesłanie abstraktu na:

Abstrakty - 9. Forum Matematyków Polskich (us.edu.pl)

(oraz idealnie potwierdzenie emailowe do mnie, że udało Ci się posłać).

Set Theory Workshop "Compactness and Cardinal Invariants" Vienna, May 2, 2024

Conference

5/3/2024

Set Theory Workshop at OMP and Kolingasse Together with our Czech research partners we invite you to this Workshop. Time and location: Morning session 9:00-12:00, Oskar-Morgenstern-Platz 1, SR 6, 1st fl. Afternoon session 14:00-17:55, Kolingasse 14-16, SR 1, 1st fl. Zoom info: Please contact petra.czarnecki@univie.ac.at Program: 09 : 00 − 9 : 30 Andrea Medini 09 : 35 − 10 : 05 Šárka Stejskalová 10 : 05 − 10 : 40 COFFEE 10 : 40 − 11 : 10 Corey Switzer 11 : 15 − 11 : 45 Serhii Bardyla 12 : 00 − 14 : 00 LUNCH 14 : 00 − 14 : 30 Chris Lambie-Hanson 14 : 35 − 15 : 05 Jonathan Cancino 15 : 05 − 15 : 40 COFFEE 15 : 40 − 16 : 10 Julia Millhouse 16 : 15 − 16 : 45 Tristan van der Vlugt 16 : 50 − 17 : 20 Martina Iannella 17 : 25 − 17 : 55 Claudio Agostini Organizer: Vera Fischer (U Wien) Radek Honzik (Charles University, Prague, CZ) If you have any questions, please write to the organizers. For more information see the program.

Link to more info

Tagged: Andrea Medini, Šárka Stejskalová, Corey Switzer, Serhii Bardyla, Chris Lambie-Hanson, Jonathan Cancino, Julia Millhous, Tristan van der Vlugt, Martina Iannella, Claudio Agostini

UPDATE: This Week in Logic at CUNY

This Week in Logic at CUNY

4/29/2024 19:49:19

Hi everyone,

Note the addition of a talk by Benjamin Prudhomme in the Computational Logic Seminar on Tuesday 4/30.

All best,

Jonas

This Week in Logic at CUNY:

*** CUNY SPRING RECESS APRIL 22 - 30 ***

- - - - Monday, Apr 29, 2024 - - - -

Rutgers Logic Seminar
Monday Apr 29, 3:30pm Hill Center, Hill 705

Gabe Goldberg, Berkeley

Generalizations of the Ultrapower Axiom

Logic and Metaphysics Workshop
Date: Monday, April 29, 4.15-6.15pm (NY time)
Room: Graduate Center Room 7395

Anandi Hattiangadi (Stockholm).
Title: Physicalism, intentionality and normativity: The essential explanatory gap

Abstract: In this paper, I present an explanatory gap argument against the view that the semantic facts are fully grounded in the physical facts. Unlike traditional explanatory gap arguments, which stem from the failure of analytic reductive explanation, the explanatory gap I point to stems from the failure of metaphysical explanation. I argue for the following theses. (i) Physicalist grounding claims are metaphysically necessary, if true. (ii) To be explanatorily adequate, these grounding claims must be deducible from facts about essence. (iii) Semantico-physical grounding claims are possibly false, not (only) because they are conceivably false, but because they cannot be deduced from facts about essence. (iv) Semantic properties are essentially weakly normative: it lies in their natures to have correctness conditions and subjectively rationalize—rather than merely cause—behaviour. This gives rise to an explanatory gap that indicates that the semantic facts are not fully grounded in the physical facts.

- - - - Tuesday, Apr 30, 2024 - - - -

Computational Logic Seminar
Spring 2024 (online)
Tuesday, April 30
Time 2:00 - 4:00 PM (EDT)
zoom link: ask Sergei Artemov sartemov@gmail.com
Speaker: Benjamin PrudHomme, Graduate Center CUNY
Title: On Game Theory and Epistemic Logic

Abstract: Review of basic game theory and epistemic game theory concepts, including strictly competitive games, pure and mixed strategy Nash equilibria, rationalizability, models of knowledge, distinction between mutual and common knowledge. Review of proofs of when a game has a Nash equilibrium, Nash's Theorem, Muddy Children Problem. Discussions of current and potential future efforts to utilize logic in developing a more comprehensive theory of pure strategy solutions.

- - - - Wednesday, May 1, 2024 - - - -

- - - - Thursday, May 2, 2024 - - - -

- - - - Friday, May 3, 2024 - - - -

Model Theory Seminar
CUNY Graduate Center
Friday May 3, 12:30pm NY time, Room: 6495

Athar Abdul-Quader, Purchase College
Genericity in models of arithmetic

In this talk, I plan to explore a few notions of 'genericity' in the context of models of arithmetic. I will recall the notion of genericity borrowed from set-theory, used by Simpson to prove that every countable model of PA has an expansion to a pointwise definable model of PA*. I will then explore other notions of genericity inspired by more model-theoretic contexts. One such notion is 'neutrality': in a model M, we say an undefinable set X is neutral if the definable closure relation in (M, X) is the same as in M. Another notion, inspired by work done on model-theoretic genericity by Chatzidakis and Pillay, is called CP-genericity. I will explore these notions and outline some results, including: (1) every model of PA has a neutral set which is not CP-generic, (2) every countable model of PA has a CP-generic which is not neutral (and in fact, fails neutrality spectacularly: ie, we can find a CP-generic where the expansion is pointwise definable), and (3) every countable model of PA has a neutral CP-generic. This talk touches on work contained in two papers, one of which was joint work with Roman Kossak, and the other was joint work with James Schmerl.

Set Theory Seminar
CUNY Graduate Center
Friday, May 3, 12:30pm NY time
Virtual: Please email Victoria Gitman (vgitman@gmail.com) for meeting id.

Spencer Unger, University of Toronto
Iterated ultrapower methods in analysis of Prikry type forcing

We survey some old and new results in singular cardinal combinatorics whose proofs can be phrased in terms of iterated ultrapowers and ask a few questions.

Logic Workshop
CUNY Graduate Center
Friday May 3, 2:00pm-3:30pm, Room 5417

Christian Wolf, CUNY
Computability of entropy and pressure on compact symbolic spaces beyond finite type

In this talk we discuss the computability of the entropy and topological pressure on compact shift spaces and continuous potentials . This question has recently been studied for subshifts of finite type (SFTs) and their factors (Sofic shifts). We develop a framework to address the computability of the entropy pressure on general shift spaces and apply this framework to coded shifts. In particular, we prove the computability of the topological pressure for all continuous potentials on S-gap shifts, generalized gap shifts, and Beta shifts. We also construct shift spaces which, depending on the potential, exhibit computability and non-computability of the topological pressure. We further show that the generalized pressure function is not computable for a large set of shift spaces and potentials . Along the way of developing these computability results, we derive several ergodic-theoretical properties of coded shifts which are of independent interest beyond the realm of computability. The topic of the talk is joint work with Michael Burr (Clemson U.), Shuddho Das (Texas Tech) and Yun Yang (Virginia Tech).

Next Week in Logic at CUNY:

- - - - Monday, May 6, 2024 - - - -

Logic and Metaphysics Workshop
Date: Monday, May 6, 4.15-6.15pm (NY time)
Room: Graduate Center Room 7395

Lorenzo Rossi (Turin)
Title: Alethic pluralism and Kripkean truth

Abstract: According to alethic pluralism, there is more than one way of being true: truth is not unique, in that there is a plurality of truth properties each of which pertains to a specific domain of discourse. This paper shows how such a plurality can be represented in a coherent formal framework by means of a Kripke-style construction that yields intuitively correct extensions for distinct truth predicates. The theory of truth it develops can handle at least three crucial problems that have been raised in connection with alethic pluralism: mixed compounds, mixed inferences, and semantic paradoxes.

Note: This is joint work with Andrea Iacona (Turin) and Stefano Romeo (Turin).

- - - - Tuesday, May 7, 2024 - - - -

- - - - Wednesday, May 8, 2024 - - - -

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: Juan Orendain, Case Western Univeristy.

Date and Time: Wednesday May 8, 2024, 7:00 - 8:30 PM. ZOOM TALK.

Title: Canonical squares in regularly framed bicategories.

- - - - Thursday, May 9, 2024 - - - -

- - - - Friday, May 10, 2024 - - - -

Logic Workshop
CUNY Graduate Center
Friday May 10, 2:00pm-3:30pm, Room 5417

Roman Kossak, CUNY
The lattice problem for models of arithmetic

The lattice problem for models of PA is to determine which lattices can be represented either as lattices of elementary substructures of a model of PA or, more generally, which can be represented as lattices of elementary substructures of a model N that contain a given elementary substructure M of N.

Since the 1970's, the problem generated much research with highly nontrivial results with proofs combining specific methods in the model theory of arithmetic with lattice theory and various combinatorial theorems. The problem has a definite answer in the case of distributive lattices, and, despite much effort, there are still many open questions in the nondistributive case. I will briefly survey some early results and present a few proofs that illustrate the difference between the distributive and nondistributive cases.

- - - - Other Logic News - - - -

CONFERENCE ANNOUNCEMENT

Northeast Model Theory Day

We are pleased to announce that Wesleyan University in Middletown, CT will be hosting a Northeast Model Theory Day on Saturday May 4, 2024. This one-day meeting is the first in what we hope will become an annual series, bringing together those interested in model theory from across the region.

Speakers:
Paul Baginski (Fairfield)
Artem Chernikov (Maryland)
Alf Dolich (CUNY)
Alexei Kolesnikov (Towson)

All are welcome, but please register by Monday, April 22nd. Limited travel support is available. For more information and registration, please visit http://nemtd24.wescreates.wesleyan.edu/

NEMTD 2024 sponsored by the Mid-Atlantic Mathematical Logic Seminar (NSF grant #DMS-1834219) and the Wesleyan Department of Mathematics and Computer Science.
Organizers: Alex Kruckman, Rehana Patel, Alex Van Abel. Contact akruckman@wesleyan.edu with any questions.

- - - - 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.

Cross-Alps Logic Seminar (speaker: Spencer Unger)

Cross-Alps Logic Seminar

4/29/2024 6:58:52

On Friday 03.05.2024 at 16.00 CEST
Spencer Unger (University of Toronto)
will give a talk on
Iterated ultrapower methods

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

4/28/2024 22:30:00

This Week in Logic at CUNY:

*** CUNY SPRING RECESS APRIL 22 - 30 ***

- - - - Monday, Apr 29, 2024 - - - -

Rutgers Logic Seminar
Monday Apr 29, 3:30pm Hill Center, Hill 705

Gabe Goldberg, Berkeley

Generalizations of the Ultrapower Axiom

Logic and Metaphysics Workshop
Date: Monday, April 29, 4.15-6.15pm (NY time)
Room: Graduate Center Room 7395

Anandi Hattiangadi (Stockholm).
Title: Physicalism, intentionality and normativity: The essential explanatory gap

Abstract: In this paper, I present an explanatory gap argument against the view that the semantic facts are fully grounded in the physical facts. Unlike traditional explanatory gap arguments, which stem from the failure of analytic reductive explanation, the explanatory gap I point to stems from the failure of metaphysical explanation. I argue for the following theses. (i) Physicalist grounding claims are metaphysically necessary, if true. (ii) To be explanatorily adequate, these grounding claims must be deducible from facts about essence. (iii) Semantico-physical grounding claims are possibly false, not (only) because they are conceivably false, but because they cannot be deduced from facts about essence. (iv) Semantic properties are essentially weakly normative: it lies in their natures to have correctness conditions and subjectively rationalize—rather than merely cause—behaviour. This gives rise to an explanatory gap that indicates that the semantic facts are not fully grounded in the physical facts.

- - - - Tuesday, Apr 30, 2024 - - - -

- - - - Wednesday, May 1, 2024 - - - -

- - - - Thursday, May 2, 2024 - - - -

- - - - Friday, May 3, 2024 - - - -