Organizatorzy

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

Informacje

środy, 16:15 , sala: 5050

Dziedziny badań

Topologia i teoria mnogości

Lista referatów

11 kwietnia 2018 16:15
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 …
21 marca 2018 16:15
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, …
14 marca 2018 16:15
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. …
7 marca 2018 16:15
Witold Marciszewski (University of Warsaw)
On zero-dimensional subspaces of Eberlein compacta
Let us recall that a compact space K is Eberlein compact if it can be embedded into some Banach space X equipped with the weak topology. We will discuss the following problem: Does every nonmetrizable …
28 lutego 2018 16:15
TOMASZ NATKANIEC (University of Gdańsk)
PERFECTLY EVERYWHERE SURJECTIVE BUT NOT JONES FUNCTIONS
Given a function f : R → R we say that • f is perfectly surjective (f ∈ PES) if f[P] = R for every perfect set P; • f is a Jones function (f …
24 stycznia 2018 16:15
Taras Banakh (Lviv National University and UJK Kielce)
Null-finite sets in metric groups and their applications
We shall introduce a new family of "small" sets which is tightly connected with two well known $\sigma$-ideals: of Haar-null sets and of Haar-meager sets. We define a subset $A$ of a topological group $X$ …
17 stycznia 2018 16:15
Szymon Żeberski (Wrocław University of Technology)
Nonmeasurable sets and unions with respect to tree ideals
We consider a notion of nonmeasurablity with respect to Marczewski and Marczewski-like tree ideals $s_0$, $m_0$, $l_0$, and $cl_0$. We show that there exists a subset $A$ of the Baire space $\omega^\omega$ which is $s$-, …
20 grudnia 2017 16:15
Damian Sobota (Kurt Gödel Research Center for Mathematical Logic)
Convergence of measures and cardinal characteristics of the continuum
Let A be a Boolean algebra. We say that A has the Nikodym property if every pointwise convergent sequence of measures on A is weak* convergent. Similarly, A has the Grothendieck property if every weak* …
13 grudnia 2017 16:15
Tomasz Cieśla (University of Warsaw)
Homeomorphism relation of locally connected continua is complete
Every Borel action of a Polish group G on a Polish space X gives rise to a relation ~ given by x ~ y if and only if x and y are in the same …
29 listopada 2017 16:15
Ziemowit Kostana (University of Warsaw)
Non-measurability of the algebraic sums of sets of real numbers
Consider the following problems: 1. If A is a meagre (null) subset of the real line, does there necessarily exist a set B such that the algebraic sum A+B doesn't have the Baire property (is …
22 listopada 2017 16:15
Maciej Malicki (Warsaw School of Economics)
Generic representations of countable groups - part 2
The fact that a Polish group G has a comeager conjugacy class can be expressed in the language of representations: it is equivalent to the existence of a generic representation of the group of integers …
15 listopada 2017 16:15
Maciej Malicki (Warsaw School of Economics)
Generic representations of countable groups
The fact that a Polish group G has a comeager conjugacy class can be expressed in the language of representations: it is equivalent to the existence of a generic representation of the group of integers …
8 listopada 2017 16:15
Yurii Khomskii (Hamburg University)
Definable Maximal Independent Families
Maximal independent families are combinatorial objects that have applications in various areas of mathematics. A maximal independent family can be constructed using the Axiom of Choice, and an old result of Arnold Miller shows that …
25 października 2017 16:15
Marek Balcerzak (Politechnika Łódzka)
The Baire category of ideal convergent subseries and rearrangements of a divergent series
Let I be a 1-shift-invariant ideal on N with the Baire property. Assume that a series with terms in a real Banach space X is not unconditionally convergent. We show that the sets of I-convergent …
18 października 2017 16:15
Michał Korch (UW)
Specjalne podzbiory uogólnionej przestrzeni Cantora II / Special subsets of the generalized Cantor space II
Streszczenie: Mój referat zacznie się od wprowadzenia uogólnionej przestrzeni Cantora 2^\kappa dla regularnej nieprzeliczalnej liczby kardynalnej \kappa. Przestrzeń ta wyposażona jest w tak zwaną ograniczoną topologię, generowaną przez zbiory wszystkich przedłużeń funkcji częściowych. W ostatnich …