Upcoming colloquiums

Wednesday, 2025-02-12

Adam Kwela (University of Gdansk)

  • Title: Ideal versions of the bounding number
  • Abstract: I will discuss several ideal versions of the bounding number and mention some of their applications.
  • Location: IMPAN (Gdansk branch), Antoniego Abrahama 18, 81-825 Sopot
  • Time: 16:45

Wednesday, 2025-03-12

Vera Fischer(University of Vienna)

  • Title: TBA
  • Abstract: TBA
  • Location: IMPAN (Gdansk branch), Antoniego Abrahama 18, 81-825 Sopot
  • Time: 16:45

Past colloquiums

Wednesday, 2025-01-22

Boriša Kuzeljević (University of Novi Sad)

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  • Title: Rudin-Keisler ordering of ultrafilters
  • Abstract: We will present some basic facts about the Rudin-Keisler ordering of ultrafilters, as well as some recent results about the structure of this ordering in the class of P-point ultrafilters. The results I will present are joint work with Dilip Raghavan and Jonathan Verner.
  • Location: IMPAN (Gdansk branch), Antoniego Abrahama 18, 81-825 Sopot
  • Time: 16:45

Wednesday, 2024-12-11

Chris Lambie-Hanson (Institute of Mathematics Czech Academy of Sciences)

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  • Title: Nonvanishing higher derived limits and characteristics of ideals
  • Abstract: Recent years have seen a number of developments in the application of set-theoretic techniques to the study of derived functors, and in particular to the derived functor of the inverse limit. In this talk, we will consider a family of inverse systems indexed by ideals and will discuss the effect that certain characteristics of these ideals have on the vanishing of the derived limits of the corresponding systems. In particular, this will yield a proof of the fact that, if all derived limits of a particular class of inverse systems known as \(\Omega\)-systems vanish, then the continuum must be at least \(\aleph_{\omega+1}\), thus answering a question of Bannister. The talk will contain joint work with Matteo Casarosa.
  • Location: IMPAN (Gdansk branch), Antoniego Abrahama 18, 81-825 Sopot
  • Time: 16:45

Wednesday, 2024-11-27

Piotr Borodulin-Nadziejać (University of Wroclaw)

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  • Title: Combinatorial Banach spaces
  • Abstract: I will present a way of generating Banach spaces from infinite graphs with several examples and a structural theorem.
  • Location: IMPAN (Gdansk branch), Antoniego Abrahama 18, 81-825 Sopot
  • Time: 16:45

Wednesday, 2024-11-13

Rafał Filipów (UG)

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  • Title: Distinguishing between sequentially compact spaces via Katetov order on ideals
  • Abstract:The talk is based on the paper "A unified approach to Hindman, Ramsey and van der Waerden spaces" (https://doi.org/10.1017/jsl.2024.8) written by Krzysztof Kowitz, Adam Kwela and myself. First, I'm going to survey known results that motivated us for looking for a unified approach to this subject. Next, I will show how to encompass in one manner distinct kinds of convergence in topological spaces considered so far. Finally, I'll show that various results from many papers can be obtained from one theorem.
  • Location: IMPAN (Gdansk branch), Antoniego Abrahama 18, 81-825 Sopot
  • Time: 16:45

Wednesday, 2024-10-30

Boban Veličković (IMJ-PRG)

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  • Title: Nice Infinitary Logics
  • Abstract: We define a new class of infinitary logics \(L^1_{\kappa,\alpha}\) generalizing Shelah's logic \(L^1_\kappa\). If \(\kappa=\beth_{\kappa}\) and \(\alpha<\kappa\) is infinite then our logic coincides with \(L^1_\kappa\). We study the relation between these logics for different parameters \(\kappa\) and \(\alpha\). We give many examples of classes of structures that can or cannot be defined in these logics. Finally, we give a different version of Lindström's Theorem for \(L^1_\kappa\) in terms of the \(\phi\)-submodel relation. This is Joint work with J. Väänänen.
  • Location: IMPAN (Gdansk branch), Antoniego Abrahama 18, 81-825 Sopot
  • Time: 16:30

On the mathematical sublime

Juliette Kenedy (University of Helsinki)
(Part of Simon’s Semester Program)

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  • Venue: University of Gdansk, Department of Mathematics, Room D003
  • Day: December 06, 2023
  • Time: 16:00-17:00
  • Notes: Part of Simon’s Semester Program

Inner models from extended logics

Jouko Vaananen (University of Helsinki)

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  • Venue: University of Gdansk, Department of Mathematics, Room D003
  • Day: December 02, 2023
  • Time: 17:00-18:00
  • Notes: Part of Simon’s Semester Program

Strong forcing axioms and the continuum problem

Matteo Viale (University of Torino)

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  • Day: November 23, 2023
  • Notes: Part of Simon’s Semester Program
Read abstract A topological approach to forcing axioms considers them as strong forms of the Baire category theorem; an algebraic approach describes certain properties of "algebraic closure" for the universe of sets that can be derived from them. The goal of the talk is to outline the link betwen the geometric and algebraic points of view. The talk is meant for a general mathematical audience. In particular familiarity with logic or set theory is not assumed.

The *-version of Martin’s Maximum

Ralf Schindler (University of Münster)

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  • Venue: University of Gdansk, Department of Mathematics, Room D003
  • Day: November 02, 2023
  • Time: 16:45-17:45
  • Notes: Part of Simon’s Semester Program

Higher forcing axioms

Boban Velickovic (IMJ-PRG)

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  • Venue: University of Gdansk, Department of Mathematics, Room D003
  • Day: November 02, 2023
  • Time: 15:30-16:30
  • Notes: Part of Simon’s Semester Program

Mouse Pairs and Soulsin Cardinals

John Steel (UC Berkeley)

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  • Venue: University of Gdansk, Department of Mathematics
  • Day: October 26, 2023
  • Notes: Part of Simon’s Semester Program

Continuous logic and equivalence relations

Maciej Malicki (IMPAN)

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  • Day: October 14, 2022

The Ultrafilter Axiom (4 Lectures)

Gabe Goldberg

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  • Day: July 25-August 6, 2022

Set theory and the Continuum Hypothesis

Ralf Schindler (University of Münster)

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  • Day: February 9, 2022
Read abstract - In a 2021 Annals paper, D. Aspero and the speaker showed that two prominent axioms of set theory which were introduced independently from one another in the late 80's early 90's and which both decide the size of the continuum are compatible, in fact one implies the other. Both axioms are so-called forcing axioms which are also exploited in other areas of mathematics. I am going to provide an accessible introduction to our result.