Organizers

prof. dr hab. Witold Marciszewski
prof. dr hab. Piotr Zakrzewski

Information

Wednesdays, 4:15 p.m. , room: 5050

Research fields

Topology and Set Theory

List of talks

Nov. 21, 2018, 4:15 p.m.
Grzegorz Plebanek (University of Wrocław)
On Cartesian products of compact lines
This is joint work with Gonzalo Martinez Cervantes. By a compact line we mean a compact space which topology is defined by a linear order. Answering a problem posed by Mardesic, we show that n-fold …
Nov. 14, 2018, 4:15 p.m.
Arturo Antonio Martínez Celis Rodríguez (IMPAN)
Ultrafilters related to the Michael space problem
A Lindelöf Topological space is Michael if it has non-Lindelöf product with the space of the irrational numbers. These kind of spaces were introduced by Ernest Michael in 1963 and it is still unknown if …
Nov. 7, 2018, 4:15 p.m.
Ali Enayat (University of Gothenburg, Sweden)
Models of arithmetic meet set theory and topology
The first part of the talk is expository and provides a general introduction to nonstandard models of arithmetic, and the various ways they interact with set theory and topology. The second part focuses on recent …
Oct. 24, 2018, 4:15 p.m.
Paweł Krupski (Wrocław University of Science and Technology)
Complexity of homeomorphism relations on some classes of compacta
This is a joint work with Benjamin Vejnar (https://arxiv.org/pdf/1808.08760.pdf). We prove that the homeomorphism relation between compact spaces can be continuously reduced to the homeomorphism equivalence relation between absolute retracts which strengthens and simplifies recent …
Oct. 17, 2018, 4:15 p.m.
Roman Pol (University of Warsaw)
On a problem of Talagrand concerning separately continuous functions
This is a joint work with Volodymyr Mykhaylyuk (a preliminary version of our paper is on arXiv: https://arxiv.org/pdf/1809.05799.pdf) M.Talagrand [Math.Ann.270(1985),Probleme 3] stated the following problem (recalled recently in Guirao, V.Montesinos, V.Zizler, Open problems in …
Oct. 10, 2018, 4:15 p.m.
Viktoriia Brydun (Lviv National University)
Fuzzy metrization of the spaces of idempotent measures
The talk will be dedicated to idempotent mathematics (better known as tropical mathematics) and category theory. The idempotent measures (Maslov measures) are counterparts of the probability measures in the idempotent mathematics. The main result …
June 13, 2018, 4:15 p.m.
Kazimierz Alster (UKSW)
Gra Telgarskiego a multiplikatywność parazwartości
Ogólnym problemem dotyczącym multiplikatywności parazwartości jest pytanie o charakteryzację klasy P przestrzeni parazwartych, których iloczyn kartezjański z dowolną przestrzenią parazwartą jest parazwarty a także związane z nim problemy: Czy klasa P jest zamknięta ze względu …
June 6, 2018, 4:15 p.m.
Piotr Szewczak (Cardinal Stefan Wyszyński University in Warsaw)
Products of Luzin-type sets with combinatorial properties
A topological space is Menger if for any sequence U1, U2, … of open covers of the space, there are finite subsets F1, F2, … of U1, U2, …, respectively, such that the union of …
May 23, 2018, 4:15 p.m.
Kazimierz Alster (UKSW)
Gra Telgarskiego a multiplikatywność parazwartości
Ogólnym problemem dotyczącym multiplikatywności parazwartości jest pytanie o charakteryzację klasy P przestrzeni parazwartych, których iloczyn kartezjański z dowolną przestrzenią parazwartą jest parazwarty a także związane z nim problemy: Czy klasa P jest zamknięta ze względu …
May 16, 2018, 4:15 p.m.
Julien Melleray (Institut Camille Jordan, Université Lyon 1)
Full groups of minimal homeomorphisms of the Cantor space
The first part of the talk will be an introduction to the theory of minimal homeomorphisms and their full groups (and why these objects are interesting). In the second talk I'll sketch the proof of …
May 9, 2018, 4:15 p.m.
Rafał Filipów (University of Gdańsk)
Ideal convergence versus matrix summability
Ideal convergence and matrix summability are examples of extensions of the ordinary convergence of sequences of reals to a larger class of sequences (i.e. ordinary convergent sequences remain convergent to the same limits and there …
April 25, 2018, 4:15 p.m.
Andrzej Szymański (Cardinal Stefan Wyszyński University in Warsaw)
KKM Theorem: From L*-operators to a Renting Problem
- The abstract of the talk
April 11, 2018, 4:15 p.m.
Roman Pol (University of Warsaw)
On a paper by M.V.Ferrer, S.Hernandez and D.Shakhmatov "A countable free closed non-reflexive subgroup of Z^continuum", Proc.AMS 145(2017).
An abelian topological group H is (Pontrjagin) reflexive if the natural homomorphism from H into the group H^^ of characters on the group of characters on H is a homeomorphism of H onto H^^ (as …
March 21, 2018, 4:15 p.m.
Piotr Szewczak (Cardinal Stefan Wyszyński University in Warsaw)
The Haar measure problem
An old problem asks whether every compact group has a Haar-nonmeasurable subgroup. A series of earlier results reduce the problem to infinite metrizable profinite groups. We provide a positive answer, assuming a weak, potentially provable, …
March 14, 2018, 4:15 p.m.
Ralf Schindler (Department for Mathematical Logic and Foundational Research, University of Munster)
"Paradoxical" sets with no well-ordering of the reals
By a Hamel basis we mean a basis for the reals, R, construed as a vecor space over the field of rationals. In 1905, G. Hamel constructed such a basis from a well-ordering of R. …