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

28 lutego 2024 16:15
Robert Simon
Paradoxical colouring rules
A colouring rule is a way to determine a function from a probability space to a set of colours based on the colours of finitely many measure preserving transformations. It is paradoxical if there is …
24 stycznia 2024 16:15
Taras Banakh (Ivan Franko National University of Lviv and UJK Kielce)
Strongly rigid countable Hausdorff spaces
A topological space $X$ is strongly rigid if every no-identity continuous self-map of $X$ is constant. Among known examples of strongly rigid spaces one can recall the famous Cook continua. In fact, every strongly rigid …
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10 stycznia 2024 16:15
Piotr Szewczak (Cardinal Stefan Wyszyński University in Warsaw)
Concentrated sets in the Miller model
A set of reals X is concentrated if it is uncountable and there is a countable subset D of X such that for each open set U containing D the set X\U is countable. Using …
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20 grudnia 2023 16:15
Zdeněk Silber (IM PAN)
A countably tight P (K) space admitting a nonseparable measur)
In the talk we focus on the relation of countable tightness of the space P(K) of Radon probabilty measures on a compact Hausdorff space K and of existence of measures in P(K) that have uncountable …
13 grudnia 2023 16:15
Maciej Malicki (IM PAN)
Compacta and their homeomorphism groups from posets, part 2
Very recently A. Bartoš, T. Bice and A. Vignati discovered a duality, generalizing the Stone duality, between second countable T_1 compacta and graded omega-posets. Their approach allows for elementary combinatorial constructions, in the spirit of …
6 grudnia 2023 16:15
Adam Bartoš ("An introduction to abstract Fraïssé theory") and Wiesław Kubiś ("Uncountable homogeneous structures") (Institute of Mathematics of the Czech Academy of Sciences)
"An introduction to abstract Fraïssé theory" and "Uncountable homogeneous structures"
"An introduction to abstract Fraïssé theory": We give a gentle introduction to abstract countable discrete Fraïssé theory. First, we recall three classical examples of ultrahomogeneous structures: the linear order of the rationals, the random graph, …
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29 listopada 2023 16:15
Maciej Malicki (IM PAN)
Compacta and their homeomorphism groups from posets
Very recently A. Bartoš, T. Bice and A. Vignati discovered a duality, generalizing the Stone duality, between second countable T_1 compacta and graded omega-posets. Their approach allows for elementary combinatorial constructions, in the spirit of …
22 listopada 2023 16:15
Jindrich Zapletal (University of Florida)
Fraenkel-Mostowski models revisited
A dynamical ideal is a group G acting on a set X, together with an ideal I on X invariant under the action. A dynamical ideal comes with an associated model of ZF set theory. …
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8 listopada 2023 16:15
David Chodounsky (Institute of Mathematics of the Czech Academy of Sciences)
Games for chromatic numbers of analytic graphs
We define games which characterize countable coloring numbers of analytic graphs on Polish spaces. These games can provide simple verification of the countable chromatic number of certain graphs. We also get a simpler proof of …
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25 października 2023 16:15
Tomasz Kochanek (University of Warsaw)
Operator semigroups in the Calkin algebra, part 2
The abstract of the talk can be found here: https://drive.google.com/file/d/1xCTvKwjFXONxqUN1NurltvhGewn6GyV7/view?usp=sharing
- abstract, part 2
18 października 2023 16:15
Tomasz Kochanek (University of Warsaw)
Operator semigroups in the Calkin algebra
The abstract of the talk can be found here: https://drive.google.com/file/d/1aMk2GrPJTYMP8PiMOKgJU4Hay5186G5s/view?usp=sharing
- abstract
11 października 2023 16:15
Jesús M. F. Castillo (Universidad de Extremadura)
A twisting of C (K)-space scrapboo)
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14 czerwca 2023 16:15
Jakub Andruszkiewicz (Doctoral School of Exact and Natural Sciences UW)
Cofinalities of the symmetric group and of the ultrapowers of ω
We consider the following cardinal invariants of the continuum: cf(Sym(ω)), being the cofinality of the group of permutations of ω, and mcf, defined as the minimal cofinality of an ultrapower of ω over any non-principal …
31 maja 2023 16:15
Piotr Koszmider (IM PAN)
Ramsey properties of the distance on nonseparable spheres
Given a nonseparable metric space (M,d) bounded by 2 we consider (A) dichotomies D_r for r in (0,2): either there is uncountable subset N of M such that d(x, y) > r for all distinct …
24 maja 2023 16:15
Grzegorz Plebanek (University of Wrocław)
Countable discrete extensions of compact lines
We consider a separable compact line K and its extension L consisting of K and a countable number of isolated points. The main object of study is the existence of a bounded extension operator E: …