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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
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May 21, 2025, 4:15 p.m.
Piotr Szewczak (Cardinal Stefan Wyszynski University in Warsaw)
Hurewicz's property and concentrated sets in the Laver model
Let X be a set of reals. The set X is Hurewicz if for any sequence of countable increasing open covers of X one can select a single element from each cover such that the …
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May 14, 2025, 4:15 p.m.
Sven Manthe (University of Bonn)
The Borel monadic theory of order is decidable
The monadic second-order theory S1S of (ℕ,<) is decidable (it essentially describes ω-automata). Undecidability of the monadic theory of (ℝ,<) was proven by Shelah. Previously, Rabin proved decidability if the monadic quantifier is restricted to …
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May 7, 2025, 4:15 p.m.
Rafał Filipów (Rafał Filipów)
Critical ideals for compact spaces and Borel complexity of sets of ideal limit points
In the first part of my talk, I will introduce an ideal conv_alpha and use it to characterize (with the aid of the Katetov order) the class of all compact countable spaces which are homeomorphic …
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April 30, 2025, 4:15 p.m.
Mikołaj Krupski (University of Warsaw)
On the class of NY compact spaces of finitely supported elements and related classes
A compact space K is NY compact (ω-Corson) if K embeds into a σ-product of compact metrizable spaces (σ-product of intervals). A combination of these definitions with a classical notion of a Valdivia compact space …
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April 16, 2025, 4:15 p.m.
Luis David Reyes Saenz (National Autonomous University of Mexico)
Q-points and Q-measures in Banach Spaces
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April 9, 2025, 4:15 p.m.
Piotr Borodulin-Nadzieja (University of Wrocław)
On Banach spaces generated by perfect graphs
We study Banach spaces generated (in a Schreier-like way) by the cliques of graphs. In particular, we show that perfect graphs generate spaces of interesting geometry. This is a joint work with Barnabas Farkas and …
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April 2, 2025, 4:15 p.m.
Jan Kostrzon (Doctoral School of Exact and Natural Sciences UW)
Generic absoluteness for a model of determinacy
I will present some recent work focused on proving a strong generic absoluteness for a minimal model that satisfies the theory AD_R + 'All sets are Universally Baire'. Such model is an example of a …
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March 26, 2025, 4:15 p.m.
Michał Pawlikowski (Łódź University of Technology)
Scales and combinatorial covering properties
A b-scale set is a subset of P(w) of the form {x_alpha : alpha < b} U Fin, where {x_alpha : alpha < b} is an unbounded set in [w]^w and for all alpha < …
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March 12, 2025, 4:15 p.m.
Marcin Penconek (University of Warsaw)
Adventures of a Mathematician in Cognitive Science
In this seminar, I will discuss how mathematics can help us understand human decision-making. Categorical decisions have been of interest to many disciplines including neuroscience. Recent advances have indicated how such decisions are computed in …
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March 5, 2025, 4:15 p.m.
Julia Ścisłowska (Doctoral School of Exact and Natural Sciences UW)
Ultrafilter orders on chainable continua
The talk will be based on the results from my master’s thesis ,,Linear orders on chainable continua", prepared under supervision of prof. Witold Marciszewski. The thesis is devoted to study families of ultrafilter orders on …
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Feb. 26, 2025, 4:15 p.m.
Witold Marciszewski (University of Warsaw)
Counting Banach spaces C(K)
The talk will be devoted to presenting the results of a joint research project with Maciej Korpalski (UWr). We studied the problem of isomorphic classification of the Banach spaces C(K) of real continuous functions on …
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Jan. 22, 2025, 4:15 p.m.
Mikołaj Krupski (UW)
Every Lindel\"of scattered subspace of a $\Sigma$-product of real lines is $\sigma$-compact (Every Lindel\"of scattered subspace of a $\Sigma$-product of real lines is $\sigma$-compact)
We prove that every Lindel\"of scattered subspace of a $\Sigma$-product of first-countable spaces is $\sigma$-compact. In particular, we obtain the result stated in the title. This answers some questions of Tkachuk from [Houston J. Math. …
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Jan. 8, 2025, 4:15 p.m.
Maciej Malicki (UW)
Good measures and Fraisse theory (Good measures and Fraisse theory)
A full probability measure m on the Cantor space C is called good if there exists a uniquely ergodic homeomorphism of C whose unique invariant measure is m. Ethan Akin proved that every good measure …
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Dec. 18, 2024, 4:15 p.m.
Damian Głodkowski (UW)
A small Boolean algebra that is Grothendieck but not Nikodym, part II (A small Boolean algebra that is Grothendieck but not Nikodym, part II)
The talk will be devoted to the Grothendieck and Nikodym properties concerning measures on Boolean algebras. In 1984 Talagrand showed that under the continuum hypothesis there is a Boolean algebra with the Grothendieck property and …
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Dec. 11, 2024, 4:15 p.m.
Damian Głodkowski (UW)
A small Boolean algebra that is Grothendieck but not Nikodym (A small Boolean algebra that is Grothendieck but not Nikodym)
The talk will be devoted to the Grothendieck and Nikodym properties concerning measures on Boolean algebras. In 1984 Talagrand showed that under the continuum hypothesis there is a Boolean algebra with the Grothendieck property and …
