Nie jesteś zalogowany |
Cotygodniowe seminarium badawcze
Organizatorzy
- prof. dr hab. Witold Marciszewski
- prof. dr hab. Piotr Zakrzewski
Informacje
środy, 16:15 , sala: 5050Dziedziny badań
Lista referatów
-
1 grudnia 2021 16:15
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 …
-
-
17 listopada 2021 16:15
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 …
-
3 listopada 2021 16:15
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 …
-
27 października 2021 16:15
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 …
-
20 października 2021 16:15
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 …
-
13 października 2021 16:15
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 …
-
9 czerwca 2021 16:15
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 …
-
2 czerwca 2021 16:15
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 …
-
26 maja 2021 16:15
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 …
-
19 maja 2021 16:15
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 …
-
12 maja 2021 16:15
Piotr Koszmider (Institute of Mathematics of the Polish Academy of Sciences)
Pure states, quantum filters and ultrafilters
We will describe how the usual notion of an ultrafilter on N extends to the notion of a maximal quantum filter. Such objects correspond to pure states of quantum systems the same way that ultrafilters …
-
5 maja 2021 16:15
Jakub Andruszkiewicz (University of Warsaw)
Shelah's proof of diamond
It is a well-known fact that the diamond principle implies CH, but the reverse implication does not hold. The situation for successor cardinals larger than the first uncountable cardinal is quite different - as proved …
-
28 kwietnia 2021 16:15
Piotr Zakrzewski (University of Warsaw)
On countably perfectly meager sets
We study a strengthening of the notion of a perfectly meager set. We say that that a subset A of a perfect Polish space X is countably perfectly meager in X if for every sequence …
-
21 kwietnia 2021 16:15
Piotr Borodulin-Nadzieja (University of Wrocław)
On forcing names for ultrafilters
We show a way to handle names for ultrafilters in the random forcing. Using this approach we reprove Kunen's theorem about long towers in the random model and Kamburelis' characterization of Boolean algebras supporting finitely …
