Previous talks this semester:
10.4.2025 at 2.15 pm. Room 403.
Kacper Kucharski (MIM UW).
A ZFC example of a Banach space of density continuum without a fundamental biorthogonal system
Abstract: "During the talk we will construct a compact scattered space K
of weight continuum such that the Banach space of continuous
functions C(K) (of density continuum) does not have a fundamental biorthogonal system. This result of Dow, Junnila and Pelant complements the
result of Todorcevic which says that PFA implies that any Banach space of density ω1
has a fundamental biorthogonal system."
3.4.2025 at 2.15 pm. Room 403.
Kamil Ryduchowski (IMPAN/MIM UW).
A short introduction to construction schemes I.
Abstract: "In this talk we will present the notion of construction schemes
(with capturing properties), introduced by Todorcevic and existing e.g., under the diamond principle.
They are combinatorial structures on ω1 resembling 2-cardinals (simplified morasses).
They provide an alternative way of using the diamond in a fashion somewhat similar to forcing,
as one can construct 'generic' objects by induction along the scheme.
During the talk we shall discuss basic definitions regarding construction schemes and use them to construct a Suslin tree."
13.03.2025 at 2.15 pm. Room 403.
Damian Głodkowski (MIM UW).
Introduction to operator K-theory for the Calkin algebra and related structures. Continuation.
13.03.2025 at 2.15 pm. Room 403.
Damian Głodkowski (MIM UW).
Introduction to operator K-theory for the Calkin algebra and related structures. Continuation.
6.03.2025 at 2.15 pm. Room 403.
Damian Głodkowski (MIM UW).
Introduction to operator K-theory for the Calkin algebra and related structures.
Abstract: "We will introduce basic notions of K-theory for C*-algebras
with special emphasis on the Calkin algebra (i.e., the algebra of bounded
operators on a separable Hilbert space modulo the ideal of compact operators)
and their relations to the Fredholm index theory.
The motivation for our considerations is the problem of the existence of automorphisms
of Calkin algebras that change the Fredholm index. It is known that the Open Coloring Axiom implies the non-existence of such automorphisms,
but the problem remains open in ZFC. We will discuss possible approaches
to the problem that combine the tools of set theory with K-theory".
Talks in the first semester of 2024-25.
Talks in the second semester of 2023-24.
Talks in the first semester of 2023-24.
Talks in the second semester of 2022-23.
Talks in the first semester of 2022-23.
Talks in the second semester of 2021-22.
Talks in the first semester of 2021-22.
Talks in the second semester of 2020-21.
Talks in the first semester of 2020-21.
Talks in the second semester of 2019-20.
Talks in the first semester of 2019-20.
Talks in the second semester of 2018-19.
Talks in the first semester of 2018-19.
Talks in the second semester of 2017-18.
Talks in the first semester of 2017-18.
Talks in the second semester of 2016-17.
Talks in the first semester of 2016-17.
Talks in the second semester of 2015-16.
Talks in the first semester of 2015-16.
Talks in the second semester of 2014-15.
Talks in the first semester of 2014-15.
Talks in the second semester of 2013-14.
Talks in the first semester of 2013-14.
Talks in the second semester of 2012-13.
Talks in the first semester of 2012-13.
Talks in the second semester of 2011-12.
Talks in the first semester of 2011-12.
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