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 października 2017 16:15
Michał Korch (UW)
Specjalne podzbiory uogólnionej przestrzeni Cantora / Special subsets of the generalized Cantor space
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 …
7 czerwca 2017 16:15
Jarosław Swaczyna (Łódź University of Technology)
Haar-like smallness in Polish groups
In locally compact Polish groups there is a very natural $\sigma$-ideal of null sets with respect to Haar-measure. In non locally compact groups there is no Haar measure, however Christensen introduced a notion of Haar-null …
31 maja 2017 16:15
Piotr Szewczak (Cardinal Stefan Wyszyński University in Warsaw)
The Scheepers property and products of Menger spaces
A topological space X is Menger if for every sequence of open covers O_1, O_2,... of the space X, there are ﬁnite subfamilies F_1\subseteq O_1, F_2\subseteq O_2,... such that their union is a cover of …
24 maja 2017 16:15
Piotr Koszmider (Institute of Mathematics of the Polish Academy of Sciences)
A nonseparable scattered C*-algebra without nonseparable commutative subalgebras
The talk is based on the paper T. Bice, P. Koszmider, A note on the Akemann-Doner and Farah-Wofsey constructions, PAMS 145 (2017), no. 2, 681–687, where we remove the continuum hypothesis from the previous construction …
17 maja 2017 16:15
Tomasz Cieśla (University of Warsaw)
Borel circle squaring - part 3
In 1925 Alfred Tarski asked whether a square is equidecomposable by isometries with a disc of the same area. This question was answered in the affirmative in 1990 by Laczkovich. In 2015 Grabowski, Mathe and …
10 maja 2017 16:15
Tomasz Cieśla (University of Warsaw)
Borel circle squaring - part 2
In 1925 Alfred Tarski asked whether a square is equidecomposable by isometries with a disc of the same area. This question was answered in the affirmative in 1990 by Laczkovich. In 2015 Grabowski, Mathe and …
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26 kwietnia 2017 16:15
Witold Marciszewski (University of Warsaw)
Extension operators and twisted sums - part 3.
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29 marca 2017 16:15
Martin Dolezal (University of Warsaw)
Sigma-porosity and infinite games
We introduce an infinite game characterizing various types of sigma-porosity for Souslin sets in terms of winning strategies. We use the game to prove and reprove some new and older inscribing theorems for sigma-ideals of …
22 marca 2017 16:15
Grzegorz Plebanek (University of Wrocław )
Boolean algebras and small independent families
We consider Boolean algebras generated by families that can be decomposed into countably many pieces so that no part contains an infinite independent sequence. The property is denoted by WRN because it is closely related …
15 marca 2017 16:15
Tomasz Cieśla (University of Warsaw)
Borel circle squaring
In 1925 Alfred Tarski asked whether a square is equidecomposable by isometries with a disc of the same area. This question was answered in the affirmative in 1990 by Laczkovich. In 2015 Grabowski, Mathe and …
8 marca 2017 16:15
Jacek Tryba (University of Gdańsk)
Homogeneity of ideals
The homogeneity family of the ideal I is a family of subsets such that the restriction of I to this subset is isomorphic to I. We say that an ideal I is homogeneous if all …
1 marca 2017 16:15
Witold Marciszewski (Uniwersytet Warszawski)
Extension operators and twisted sums - part 2.
25 stycznia 2017 16:15
Witold Marciszewski (Uniwersytet Warszawski)
Extension operators and twisted sums
11 stycznia 2017 16:15
Wiesław Kubiś (Cardinal Stefan Wyszyński University in Warsaw)
Weak amalgamation classes and their limits
We will present the construction and basic properties of limits of classes of finitely generated models satsifying some natural conditions, in particular, the weak amalgamation. This is a straightforward extension of the classical Fraisse theory …
14 grudnia 2016 16:15
Taras Banakh (Lviv National University and UJK Kielce)
On
We shall discuss recent joint results with Eliza Jablonska related to (generically) Haar-meager and Haar-null sets in Polish groups.