Mittagsseminar zur Arithmetik: Benjamin Brück & Robin J. Sroka (Münster): High-dimensional rational cohomology of arithmetric groups II
Tuesday, 04.06.2024 10:15 im Raum SRZ 216/217
A conjecture by Church-Farb-Putman predicts that the rational cohomology of SL_n(Z) vanishes in high degrees. In this series of two talks, we will explain why one might believe that this conjecture is true and describe recent progress that has been made for SL_n(Z) and related groups.
The first talk focuses on SL_n(Z). The second talk puts the results in a broader context of arithmetic groups.
Angelegt am Thursday, 23.05.2024 12:28 von Heike Harenbrock
Geändert am Thursday, 23.05.2024 12:28 von Heike Harenbrock
[Edit | Vorlage]
Wilhelm Killing Kolloquium: Prof. Dr. Dima Sinapova (Rutgers University): The tree property
Thursday, 06.06.2024 14:15 im Raum M4
In the late 19th century Cantor discovered the existence of uncountable numbers, and then went on to define a whole hierarchy of infinite cardinal numbers, in other words there are "different levels of infinity". It is natural to ask if finitary and countably infinite combinatorial objects have uncountable analogues. It turns out that the answer is yes.
We will focus on one such key combinatorial property, the tree property. A classical result from graph theory (König's infinity lemma) shows the existence of this property for countable trees. More precisely, the lemma says that every infinite, finitely branching tree has an infinite branch. We will discuss what happens in the case of uncountable trees.
Angelegt am Wednesday, 21.02.2024 14:11 von Claudia Lückert
Geändert am Tuesday, 28.05.2024 14:25 von Claudia Lückert
[Edit | Vorlage]
Mittagsseminar zur Arithmetik: Benjamin Brück & Robin J. Sroka (Münster): High-dimensional rational cohomology of arithmetric groups I
Tuesday, 28.05.2024 10:15 im Raum SRZ 216/217
A conjecture by Church-Farb-Putman predicts that the rational cohomology of SL_n(Z) vanishes in high degrees. In this series of two talks, we will explain why one might believe that this conjecture is true and describe recent progress that has been made for SL_n(Z) and related groups.
The first talk focuses on SL_n(Z). The second talk puts the results in a broader context of arithmetic groups.
Angelegt am Thursday, 23.05.2024 12:28 von Heike Harenbrock
Geändert am Thursday, 23.05.2024 12:28 von Heike Harenbrock
[Edit | Vorlage]
Mittagsseminar zur Arithmetik: Julian Quast (Duisburg-Essen): On local Galois deformation rings.
Tuesday, 11.06.2024 10:15 im Raum SRZ 216/217
In joint work with Vytautas Pa?k?nas, we show that the universal framed deformation ring of an arbitrary mod p representation of the absolute Galois group of a p-adic local field valued in a possibly disconnected reductive group G is flat, local complete intersection and of the expected dimension. In particular, any such mod p representation has a lift to characteristic 0. The work extends results of Böckle, Iyengar and Pa?k?nas in the case G=GL_n. We give an overview of the proof of this main result.
Angelegt am Tuesday, 21.05.2024 09:26 von Heike Harenbrock
Geändert am Tuesday, 21.05.2024 09:26 von Heike Harenbrock
[Edit | Vorlage]
Joan Claramunt (Madrid): A graph-theoretic characterization of a class of dynamical systems and its (C*)-algebras. Oberseminar C*-Algebren.
Tuesday, 11.06.2024 16:15 im Raum SRZ 216/217
We present a graph-theoretic model for dynamical systems given
by a homeomorphism f on the Cantor set X. This construction
gives a bijective correspondence between such dynamical systems
(X,f) and a subclass of two-colored Bratteli separated graphs.
We use this construction in order to write any dynamical system
of our interest as an inverse limit of a sequence of (what we
call) generalized finite shifts. This enables us to compute the
associated Steinberg algebra (resp. C*-algebra) of the dynamical
systems as colimits of the graph algebras (resp. graph
C*-algebras) associated with the different levels of the
corresponding separated graph.
In subsequent work we plan to apply this theory to relate the
type semigroup of the dynamical system with the graph monoid of
the corresponding separated graph, and with the non-stable
K-theory of the Steinberg algebra.
This is joint work with Pere Ara (Universitat Autònoma de
Barcelona).
Angelegt am Tuesday, 07.05.2024 07:48 von Elke Enning
Geändert am Tuesday, 07.05.2024 07:48 von Elke Enning
[Edit | Vorlage]
Claudius Zibrowius (Ruhr-Universität Bochum): Khovanov homology and Conway mutatio
Wednesday, 12.06.2024 16:30 im Raum M4
Abstract: What has homological mirror symmetry ever done for you? I will give my personal answer to that question and discuss joint work in progress with Liam Watson and Artem Kotelskiy concerning the behaviour of Khovanov homology under Conway mutation.
Angelegt am Wednesday, 24.04.2024 07:17 von Claudia Rüdiger
Geändert am Wednesday, 24.04.2024 07:17 von Claudia Rüdiger
[Edit | Vorlage]