You are not logged in |
Weekly research seminar
Organizers
- prof. dr hab. Witold Marciszewski
- prof. dr hab. Piotr Zakrzewski
Information
Wednesdays, 4:15 p.m. , room: 5050Research fields
List of talks
-
Jan. 19, 2022, 4:15 p.m.
Wiesław Kubiś (Cardinal Stefan Wyszyński University in Warsaw and Institute of Mathematics of the Czech Academy of Sciences)
Abstract evolution systems, amalgamation and homogeneity
An evolution system is just a category with a distinguished class of arrows, called transitions. This concept, in particular, generalizes abstract rewriting system. It turns out that evolution systems with amalgamation provide a good framework …
-
Jan. 12, 2022, 4:15 p.m.
Maciej Malicki (IMPAN)
Large conjugacy classes and weak amalgamation
Ivanov, and later Kechris and Rosendal, characterized the existence of dense or comeager (diagonal) conjugacy classes in automorphism groups of certain classes of Fraïssé limits. I will show how these results can be extended to …
-
Dec. 15, 2021, 4:15 p.m.
Sławomir Solecki (Cornell University)
Closed groups generated by generic measure preserving transformations
The behavior of a measure preserving transformation, even a generic one, is highly nonuniform. In contrast to this observation, a different picture of a very uniform behavior of the closed group generated by a generic …
-
Dec. 8, 2021, 4:15 p.m.
Paul Szeptycki (York University)
On a topological Ramsey theorem
This is joint work with Wiesław Kubiś. We introduce natural strengthenings of sequential compactness called the $r$-Ramsey property for each natural number $r\geq 1$. We prove that metrizable compact spaces are $r$-Ramsey for all $r$ …
-
Dec. 1, 2021, 4:15 p.m.
Piotr Szewczak (Cardinal Stefan Wyszyński University in Warsaw)
Products of Hurewicz, Menger and Lindelof spaces - a continuation
We consider products of general topological spaces with Hurewicz’s, Menger’s and Lindelof’s covering properties. Assuming the Continuum Hypothesis, we prove that every productively Lindelof space is productively Menger, and every productively Menger space is productively …
-
Nov. 24, 2021, 4:15 p.m.
Alberto Salguero Alarcón (Universidad de Extremadura, Badajoz, Spain)
K)-space is not a three-space propert (To be a C)
In the setting of Banach spaces, a property P is said to be a three-space property if whenever a Banach space X has a subspace Y so that both Y and the quotient space X/Y …
-
Nov. 17, 2021, 4:15 p.m.
Jan van Mill (University of Amsterdam)
Universal autohomeomorphisms of $N^*$
This is joint work with Klaas Pieter Hart. We study the existence of universal autohomeomorphisms of $N^*$. We prove that CH implies there is such an autohomeomorphism and show that there are none in any …
-
Nov. 3, 2021, 4:15 p.m.
Piotr Szewczak (Cardinal Stefan Wyszyński University in Warsaw)
Products of Hurewicz, Menger and Lindelof spaces
We consider products of general topological spaces with Hurewicz’s, Menger’s and Lindelof’s covering properties. Assuming the Continuum Hypothesis, we prove that every productively Lindelof space is productively Menger, and every productively Menger space is productively …
-
Oct. 27, 2021, 4:15 p.m.
Grzegorz Plebanek (University of Wrocław)
On kappa-Corson compacta
A compact space is `Corson compact' if it can be embedded into some product of real lines in such a way that the support of every element is countable; kappa-Corson compactness is defined in the …
-
Oct. 20, 2021, 4:15 p.m.
Jacek Tryba (University of Gdańsk)
Different kinds of density ideals
We consider several kinds of ideals described by some densities. We present connections between Erdos-Ulam, density, matrix summability and generalized density ideals and show that a certain inaccuracy in Farah's definition of density ideals leads …
-
Oct. 13, 2021, 4:15 p.m.
Tomasz Weiss (Cardinal Wyszyński University in Warsaw)
On the algebraic sum of a perfect set and a large subset of the reals
In M. Kysiak’s paper "Nonmeasurable algebraic sums of sets of reals", (Coll. Math., Vol. 102, No 1, 2005), the following two questions appeared. Assume that A ⊆ R is a non-meager set with the Baire …
-
June 9, 2021, 4:15 p.m.
Krzysztof Zakrzewski (University of Warsaw)
Rosenthal compacta and lexicographic products
For a metrizable space X, by B_1(X) we denote the space of real valued functions of the first Baire class on X, endowed with pointwise convergence topology. A compact space K is called Rosenthal compact …
-
June 2, 2021, 4:15 p.m.
Andrzej Nagórko (University of Warsaw)
Property A and duality in linear programming
Property A was introduced in 2000 and turns out to be of great importance in many areas of mathematics. Perhaps the most striking example is the following implication. "If group G has Property A then …
-
May 26, 2021, 4:15 p.m.
Taras Banakh (Ivan Franko National University of Lviv and UJK Kielce)
A universal coregular countable second-countable space
A Hausdorff topological space X is called superconnected (resp. coregular) if for any nonempty open sets U_1 , . . . ,U_n ⊆ X, the intersection of their closures cl(U_1)∩...∩cl(U_n) is not empty (resp. the …
-
May 19, 2021, 4:15 p.m.
Damian Sobota (Kurt Gödel Research Center, University of Vienna)
On sequences of homomorphisms into measure algebras and the Efimov problem
The starting point for my talk, based on the joint work with Piotr Borodulin-Nadzieja, is our theorem presented by him recently at this seminar, characterizing a special class of compact spaces without convergent sequences in …
