Dear Logic Community,

to celebrate the winners of the 2024 edition of the

        Dov Gabbay Prize for Logic and Foundations  

                * David Asperó and Ralf Schindler *

we will organize an Online Award Ceremony on

        Thursday, November 28, 17:00 (CET)

Program (120+x min.):

        1. Intro by ILOAF and Jury
        2. Laudatio by Joan Bagaria
        3. Talk by David Asperó and Ralf Schindler
        4. Reflections by Dov Gabbay 

Zoom meeting:

Topic: Dov Gabbay Prize Ceremony
Time: Nov 28, 2024 17:00 CET

https://uni-greifswald-de.zoom.us/j/87847702729?pwd=gysFb56N97Q3jMB8CJaDLGuMJboK2b.1

Meeting ID: 878 4770 2729
Passcode: 365632

Looking forward to see you there,

    Emil Weydert and Alexander Steen (DGP-organizers/ILOAF asbl)

    Philip Welch (Jury chair)

The announcements are updated continuously. For a list of talks in the coming weeks, please see here.

Vienna Research Seminar in Set Theory
Time: Tuesday, 26 November, 15:00-16:30 CET
Speaker: T. Yamazoe, Kobe University
Title: Cichoń’s maximum with evasion number
Abstract: We show that the evasion number e can be added to Cichoń’s maximum with a distinct value. More specifically, it is consistent that ℵ1<add(N)<cov(N)<b<e<non(M)<cov(M)<d<non(N)<cof(N)<2ℵ0 holds.
This talk is related to the speaker’s upcoming talk at the Algebra seminar in TU Wien.
Information: This talk will be given in hybrid format. Please contact Petra Czarnecki for information how to participate.

Carnegie Mellon University Logic Seminar
Time: Tuesday, 26 November, 4:00 – 5:00pm Pittsburgh time (22:00 – 23:00 CET)  
Speaker: Cecilia Higgins, UC Berkeley
Title: Complexity of finite Borel asymptotic dimension
Abstract: A Borel graph is hyperfinite if it can be written as a countable increasing union of Borel graphs with finite components. It is a major open problem in descriptive set theory to determine the complexity of the set of hyperfinite Borel graphs. In a recent paper, Conley, Jackson, Marks, Seward, and Tucker-Drob introduce the notion of Borel asymptotic dimension, a definable version of Gromov’s classical notion of asymptotic dimension that strengthens hyperfiniteness and implies several nice Borel combinatorial properties. We show that the set of locally finite Borel graphs having finite Borel asymptotic dimension is $\mathbf{\Sigma}^1_2$-complete. This is joint work with Jan Grebík.
Information: See the seminar webpage.

Kobe Set Theory Seminar
Time: Wednesday, 27 November, 15:30 local time (7:30 CET)
Speaker: Sakaé Fuchino
Title: Maximality Principles and Laver generic large cardinals
Abstract: In this talk, I will review the characterization of Maximality Principles in terms of Recurrence Axioms, and prove the implication of Maximality Principles from the existence of a strong variation of Laver-generic large cardinal (a super-C(∞) P-Laver gen. ultrahuge cardinal). The presentation is going to use both the blackboads and the slides: RIMS2024-set-theory-fuchino-pf.pdf
Information: See the seminar webpage.

Leeds Set Theory Seminar
Time: Wednesday, 27 November, 13:00-14:00 local time (14:00-15:00 CET)
Speaker: tba
Title: tba
Abstract: tba
Information: Contact Hope Duncan at mmhid@leeds.ac.uk for more information.

Vienna Research Seminar in Set Theory
Time: Thursday, 28 November, 11:30-13:00 CET
Speaker: R. Chen, University of Michigan
Title: End spaces of Borel and measure-class-preserving graphs
Abstract: An important aspect of Borel dynamics and graph combinatorics concerns the large-scale topological and geometric structure of Borel trees and graphs, as made precise by the notion of an end (“connected component at infinity”) of a graph. For instance, by a result of Gaboriau and Ghys, a probability-measure-preserving graph with at least 3 ends per component must be non-amenable almost everywhere; the proof of this result uses a Borel version of Stallings’ theorem on ends of groups. We will give a survey of some recent results in this area, that all share a theme of “doing Borel topology” on spaces of ends of graphs. This talk is based on joint works with Antoine Poulin, Ran Tao, Greg Terlov, Anush Tserunyan, and Robin Tucker-Drob.
Information: This talk will be given in hybrid format. Please contact Petra Czarnecki for information how to participate.

Vienna Logic Colloquium
Time: Thursday, 28 November, 15:00 – 15:50 CET
Speaker: R. Chen, University of Michigan
Title: Structurable equivalence relations, Borel combinatorics, and countable model theory
Abstract: The theory of countable Borel equivalence relations (CBERs) provides a global framework for discussing and comparing all locally countable Borel combinatorics problems (graph colorings, group actions, etc.) at once. We present a result showing that in a precise sense, all such combinatorial problems on CBERs can be reduced to syntactic definability problems in the infinitary logic Lω1ω on countable structures. This provides a rigorous explanation of a well-known heuristic in Borel combinatorics, that many arguments amount to “doing countable combinatorics in a uniformly Borel way”, while also allowing finer distinctions to be made between different classically equivalent combinatorial problems.
This talk is based on joint works with Alexander Kechris and Rishi Banerjee.
Information: This talk will be given in hybrid format. Please contact Petra Czarnecki for information how to participate.

New York Set Theory Seminar
Time: Friday, 29 November, 11.00am New York time (17.00 CET)
Speaker: tba
Title: tba
Abstract: tba
Information: Please see the seminar webpage for the login information.

Toronto Set Theory Seminar
Time: Friday, 29 November, 1.30-3.00pm Toronto time (19.30-21.00 CET)
Speaker: Elden Elmanto
Title: tba
Abstract: tba
Information: Please see the seminar webpage for the login information. 

The announcements are updated continuously. For a list of talks in the coming weeks, please see here.

Set Theory in the UK
Time: Monday, 18 November, 11:00 – 18:00 UK time (12:00 – 19:00 CET)  
Speakers: Tristan van der Vlugt, Vienna; Allison Wang, Pittsburgh; Zachiri McKenzie, Chester
Information: Contact Benedikt Löwe for the login information.

Carnegie Mellon University Logic Seminar
Time: Tuesday, 19 November, 4:00 – 5:00pm Pittsburgh time (22:00 – 23:00 CET)  
Speaker: Cecilia Higgins, UC Berkeley
Title: Complexity of finite Borel asymptotic dimension
Abstract: A Borel graph is hyperfinite if it can be written as a countable increasing union of Borel graphs with finite components. It is a major open problem in descriptive set theory to determine the complexity of the set of hyperfinite Borel graphs. In a recent paper, Conley, Jackson, Marks, Seward, and Tucker-Drob introduce the notion of Borel asymptotic dimension, a definable version of Gromov’s classical notion of asymptotic dimension that strengthens hyperfiniteness and implies several nice Borel combinatorial properties. We show that the set of locally finite Borel graphs having finite Borel asymptotic dimension is $\mathbf{\Sigma}^1_2$-complete. This is joint work with Jan Grebík.
Information: See the seminar webpage.

Kobe Set Theory Seminar
Time: Wednesday, 20 November, 15:30 local time (7:30 CET)
Speaker: Andrés F. Uribe-Zapata
Title: Probability trees (2)
Abstract: Recently, in [UZ23], a formalization of the concept of a probability tree was introduced with the aim of proving certain results in forcing theory using finitely additive measures. In particular, these trees were used to show that random forcing is σ-FAM-linked (see [MU24]), a linkedness notion that emerged from studying the cofinality of cov(N) (see [Sh00] and [CMU24]). Probability trees also played a fundamental role in the limit step of the general theory of iterated forcing with finitely additive measures developed in [CMU24]. In this talk, we will present the formalization of the notion of probability tree, exploring some characterizations and basic properties. We will also prove that there exists a connection between probability trees of infinite height and the real line. Finally, we will show some applications of probability trees in the study of cardinal invariants. This is joint work with Diego A. Mejía and Carlos M. Parra-Londoño.
References: 
[CMUZ24] Miguel~A. Cardona, Diego~A. Mejía, and Andrés~F. Uribe-Zapata. A general theory of iterated forcing using finitely additive measures. Preprint, arXiv:2406.09978, 2024. 
[She00] Saharon Shelah. Covering of the null ideal may have countable cofinality. Fund. Math., 166(1-2):109–136, 2000. 
[MU24] Diego A. Mejía and Andrés F. Uribe-Zapata. The measure algebra adding θ-many random reals is θ-FAM-linked. Topology and its Applications. To appear, arXiv:2312.13443, 2024. 
[UZ23] Andrés F. 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://sites.google.com/view/andres-uribe-afuz/publications.
Information: See the seminar webpage.

Leeds Set Theory Seminar
Time: Wednesday, 20 November, 13:00-14:00 local time (14:00-15:00 CET)
Speaker: tba
Title: tba
Abstract: tba
Information: Contact Hope Duncan at mmhid@leeds.ac.uk for more information.

Caltech Logic Seminar
Time: Wednesday, 20 November, 12:00 – 13:00pm Pacific time (21:00 – 22:00 CET)  
Speaker: Edward Hou, Caltech
Title: Measurable domatic partitions
Abstract: Let Γ be a compact Polish group of finite Lebesgue covering dimension. For a countably infinite subset S⊆Γ, a domatic ℵ0-partition (for its Schreier graph on Γ) is a partial function f:Γ⇀N such that for every x∈Γ, one has f[S⋅x]=N. We show that a continuous domatic ℵ0-partition exists, if and only if a Baire measurable domatic ℵ0-partition exists, if and only if the topological closure of S is uncountable. A Haar measurable domatic ℵ0-partition exists for all choices of S.
We will talk about an application of this result to the theory of sum sets in Rn, and if time permits, some other examples of domatic partitions in the descriptive graph combinatorial setting. This work is based on an undergraduate thesis project under the supervision by Clinton Conley.
Information: See the seminar webpage.

Vienna Research Seminar in Set Theory
Time: Thursday, 21 November, 11:30-13:00 CET
Speaker: B. Siskind, TU Wien
Title: Turing-invariant functions under determinacy II
Abstract: This talk is part of a two-part series.
In part 1, we discussed some results about Turing-invariant functions from reals into ω1 under the Axiom of Determinacy. Today in part 2, we’ll see how these results can be used to prove Martin’s Conjecture for order-preserving functions up to the double hyperjump (and some other related things, time permitting).
Information: This talk will be given in hybrid format. Please contact Petra Czarnecki for information how to participate.

Vienna Logic Colloquium
Time: Thursday, 21 November, 15:00 – 15:50 CET
Speaker: Philipp Schlicht, University of Siena
Title: Definable hypergraphs and the Wadge hierarchy
Abstract: The open graph dichotomy states that the complete graph on the Cantor space is least among open graphs on analytic sets with respect to the ordering given by continuous graph homomorphisms. Ben Miller used dichotomies of this form to prove many interesting theorems in descriptive set theory.
I will survey some applications to the descriptive set theory of generalised Cantor spaces. I will further draw a connection to the Wadge hierarchy of generalised Cantor spaces and sketch what is currently known about its structure.
Information: This talk will be given in hybrid format. Please contact Petra Czarnecki for information how to participate.

New York Set Theory Seminar
Time: Friday, 22 November, 11.00am New York time (17.00 CET)
Speaker: Alejandro Poveda, Harvard University
Title: Identity crises phenomena between the first supercompact cardinal and Vopěnka’s Principle
Abstract: We will report on some recent results on the large cardinal hierarchy between the first supercompact cardinal and Vopěnka’s Principle. We present various consistency results as well as a conjecture as for how the large-cardinal hierarchy of Ultimate-L looks like at these latitudes. The main result will be the consistency with very large cardinals of a new Kimchi-Magidor configuration; namely, we will present a model where every supercompact cardinal is supercompact with inaccessible target points. This answers a question of Bagaria and Magidor. This configuration is a consequence of a new axiom (named A) which regards the mutual relationship between superstrong and tall cardinals. Time permitting we shall discuss the interplay between A and Ultimate-L and propose a few open questions.
Information: Please see the seminar webpage for the login information.

Toronto Set Theory Seminar
Time: Friday, 22 November, 1.30-3.00pm Toronto time (19.30-21.00 CET)
Speaker: Jing Zhang, University of Toronto
Title: Strong colorings in different dimensions (part 2)
Abstract: We will survey methods of producing strong colorings, focusing on dimensions 2 and 3, due to Todorcevic. Time permitting, we will explain some difficulty and progress in proving more general theorems. 
Information: Please see the seminar webpage for the login information. 

Hi all,

Registrations are open for a Summer School in Cetraro, Italy, September 1-5, 2025, on “Topology, dynamics, and logic in interaction”

Some funding is available to support the attendance of early-career researchers

The full list of minicourses and lecturers can be found here.

With my best regards,

Martino Lupini

The announcements are updated continuously. For a list of talks in the coming weeks, please see here.

Carnegie Mellon University Logic Seminar
Time: Tuesday, 12 November, 4:00 – 5:00pm Pittsburgh time (22:00 – 23:00 CEST)  
Speaker: Nathaniel Bannister, Carnegie Mellon University
Title: tba
Abstract: tba
Information: See the seminar webpage.

Kobe Set Theory Seminar
Time: Wednesday, 13 November, 15:30 local time (7:30 CEST)
Speaker: tba
Title: tba
Abstract: tba
Information: See the seminar webpage.

Leeds Set Theory Seminar
Time: Wednesday, 13 November, 13:00-14:00 local time (14:00-15:00 CEST)
Speaker: tba
Title: tba
Abstract: tba
Information: Contact Hope Duncan at mmhid@leeds.ac.uk for more information.

Caltech Logic Seminar
Time: Wednesday, 13 November, 12:00 – 13:00pm Pacific time (21:00 – 22:00 CEST)  
Speaker: Riley Thornton, CMU
Title: Limits of sparse hypergraphs
Abstract: Ultraproducts of pmp group actions are a useful source of examples in measurable graph theory. In combinatorics, local-global limits are a notion of limit for sparse graphs. In some sense, these two notions of limits capture the same compactness phenomenon. In this talk, I’ll generalize this theory to sparse hypergraphs and other structures, and I’ll give some applications as time permits.
Information: See the seminar webpage.

Vienna Research Seminar in Set Theory
Time: Thursday, 14 November, 11:30-13:00 CEST
Speaker: B. Siskind, TU Wien
Title: Turing-invariant functions under determinacy I
Abstract: In part 1 (today), we will discuss some results about Turing-invariant functions from reals into ω1 under the Axiom of Determinacy. In part 2, we’ll see how these results can be used to prove Martin’s Conjecture for order-preserving functions up to the double hyperjump (and some other related things, time permitting).
Information: This talk will be given in hybrid format. Please contact Petra Czarnecki for information how to participate.

Vienna Logic Colloquium
Time: Thursday, 14 November, 15:00 – 15:50 CEST
Speaker: Nigel Pynn-Coates, Universität Wien
Title: Tame pairs of transseries fields
Abstract: Transseries emerged in connection with Écalle’s work on Dulac’s problem and Dahn and Göring’s work on nonstandard models of real exponentiation, and some can be viewed as asymptotic expansions of solutions to differential equations. More recently, Aschenbrenner, Van den Dries, and Van der Hoeven completely axiomatized the elementary theory of the differential field of (logarithmic-exponential) transseries and showed that it is model complete.
This talk concerns pairs of models of this theory such that one is a tame substructure of the other in a certain sense. I will describe the model theory of such transserial tame pairs, including a model completeness result for them, which can be viewed as a strengthening of the model completeness of large elementary extensions of the differential field of transseries, such as hyperseries, surreal numbers, or maximal Hardy fields.
Information: This talk will be given in hybrid format. Please contact Petra Czarnecki for information how to participate.

New York Set Theory Seminar
Time: Friday, 15 November, 11.00am New York time (17.00 CEST)
Speaker: Philipp Schlicht, University of Siena
Title: Definable hypergraphs on large spaces
Abstract: The open graph dichotomy states that the complete graph on the Cantor space is least among open graphs on analytic sets with respect to the ordering given by continuous graph homomorphisms. Ben Miller used dichotomies of this form to prove many interesting theorems in descriptive set theory. I will survey some applications to the descriptive set theory of generalised Cantor spaces. Recent results include connections with the determinacy of a class of long games. 
Information: Please see the seminar webpage for the login information.

The announcements are updated continuously. For a list of talks in the coming weeks, please see here.

Kobe Set Theory Seminar
Time: Wednesday, 6 November, 15:30 local time (7:30 CEST)
Speaker: Yhon Castro
Title: MAD families and cardinal invariants
Abstract: Given a MAD family A, we consider the ideal IA it generates and explore the behavior of the cardinal invariants associated with the quotient algebra P(ω)/IA. In this talk, I will shed light on this topic, demonstrating the relationships of these cardinal invariants with some classical ones. Subsequently, I will discuss the construction of forcing-indestructible partitions within this algebra. This talk is based on ongoing joint work with Michael Hrušák.
Information: See the seminar webpage.

Caltech Logic Seminar
Time: Wednesday, 6 November, 12:00 – 13:00pm Pacific time (21:00 – 22:00 CEST)  
Speaker: Shaun Allison, University of Toronto
Title: A hierarchy of cli Polish groups and non-reducibility results
Abstract: We define the α-balanced Polish groups for α<ω1 and show that these form a stratification of the CLI Polish groups. Moreover, for every α, we give an example of an α-balanced Polish group and a continuous action of it on a Polish space such that the resulting orbit equivalence relation is not Borel-reducible to any such action of a β-balanced Polish group for any β<α. Recall that the CLI Polish groups are those that have compatible complete left-invariant metrics, where a metric d is invariant if d(h,h′)=d(gh,gh′) for every g, h, and h′. Our notion of α-balanced is heavily inspired by a model-theoretic rank of Deissler, and another rank notion of Malicki. We also show that this class is in fact Π11-complete, strengthening a result of Malicki.
This is joint work with Aristotelis Panagiotopoulos.
Information: See the seminar webpage.

Vienna Research Seminar in Set Theory
Time: Thursday, 7 November, 11:30-13:00 CEST
Speaker: David Chodounský, Czech Academy of Sciences, Prague
Title: Games and chromatic numbers of analytic graphs
Abstract: We define games which characterize countable coloring numbers of analytic graphs on Polish spaces. These games can provide simple verification of the countable chromatic number of certain graphs. We also get a simpler proof of a dichotomy originally proved by Adams and Zapletal: If an analytic graph has an uncountable coloring number, then it contains the graph Δ0 as a subgraph. (Here the graph Δ0 is a certain simple graph with uncountable coloring number.)
Joint work with Jindrich Zapletal.
Information: This talk will be given in hybrid format. Please contact Petra Czarnecki for information how to participate.

Vienna Logic Colloquium
Time: Thursday, 7 November, 15:00 – 15:50 CEST
Speaker: Adele Padgett, Universität Wien
Title: O-minimal definability and non-definability of the Gamma function
Abstract: O-minimality is a model-theoretic property with uses in number theory and functional transcendence. Many important functions are known to be definable in o-minimal structures when restricted to appropriate domains, including the exponential function, the Klein j function, and Weierstrass ℘ functions.
I will present joint work with P. Speissegger in which we prove that the Gamma function, which was known to be o-minimal when restricted to the positive real numbers, is in fact o-minimal on certain unbounded complex domains. A similar result holds for the Riemann zeta function.
Information: This talk will be given in hybrid format. Please contact Petra Czarnecki for information how to participate.

New York Set Theory Seminar
Time: Friday, 8 November, 11.00am New York time (11.00 CEST)
Speaker: Geoff Galgon 
Title: Distributivity and Base trees for P(κ)/<κ
Abstract: For κ a regular uncountable cardinal, we show that distributivity and base trees for P(κ)/<κ of intermediate height in the cardinal interval [ω,κ) exist in certain models. We also show that base trees of height κ can exist as well as base trees of various heights ≥κ+ depending on the spectrum of cardinalities of towers in P(κ)/<κ. These constructions answer questions of V. Fischer, M. Koelbing, and W. Wohofsky in certain models.
Information: Please see the seminar webpage for the login information.

Toronto Set Theory Seminar
Time: Friday, 8 November, 1.30-3.00pm Toronto time (19.30-21.00 CEST)
Speaker: Jing Zhang
Title: Strong colorings in different dimensions
Abstract: We will survey methods of producing strong colorings, focusing on dimensions 2 and 3, due to Todorcevic. Time permitting, we will explain some difficulty and progress in proving more general theorems. 
Information: Please see the seminar webpage for the login information.