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Wed 7.12.2022 12-14, C124
Aleksi Anttila: TBA  A remark on the dual negation in propositional/modal team semantics


Wed 14.12.2022 12-14, C124
Sabrina Gaube: TBA

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Wed 18.1.2023 12-14, C124
Vadim Weinstein: BLURRY FILTERS AND CLASSIFICATION BY COUNTABLE STRUCTURES (PART II: PROOFS)
(Joint work with Martina Lannella)

Abstract: This is a continuation of the talk given on Nov 9th 2022. In the first talk we gave an overview of the field, main ideas, and results. In this, second, talk we dive into the details of the central proofs. The same abstract as for the first talk follows:

The Stone duality gives a neat way to go back-and-forth between totally disconnected Polish spaces and countable Boolean algebras. The main ingredient is the Stone space of all ultrafilters on a Boolean algebra. In this talk we introduce a weaker concept which we call the “blurry filter”. Using blurry filters instead of ultrafilters enables one to extend the class of spaces under consideration from totally disconnected ones to a larger class. As an application of this method, we show that the following are completely classifiable by countable structures: the homeomorphism on 3-manifolds (also applicable to 2-manifolds; but this was known since 1971), and wild embeddings of Cantor sets in R³. By "classification" in this talk we mean classical Borel-reducibility.


Wed 25.1.2023 12-14, C124
TBA

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