Vorträge des SFB 1442

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Heike Harenbrock

Oberseminar p-adische Arithmetik: Analytic stacks: Claudius Heyer: Light condensed abelian groups and their cohomology

Monday, 15.04.2024 12:15 im Raum SRZ 216/217

Mathematik und Informatik



Angelegt am Thursday, 11.04.2024 09:39 von Heike Harenbrock
Geändert am Thursday, 11.04.2024 09:39 von Heike Harenbrock
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Claudia Rüdiger

Rune Haugseng (Norwegian University of Science and Technology): Equivariant ring spectra and homotopical Tambara functors

Wednesday, 10.04.2024 14:00 im Raum M6

Mathematik und Informatik

Abstract: A Tambara functor is ring-like structure, where in addition to addition and multiplication we have both additive and multiplicative norms (or transfers) for subgroups of a given finite group G; more formally, they can be defined as certain product-preserving functors out of a (2,1)-category of bispans of finite G-sets. Tambara functors often show up as equivariant analogues of commutative rings - for example, the 0th homotopy group of a genuine commutative equivariant ring spectrum is a Tambara functor. In this talk I will discuss a description of the ?-category of connective commutative equivariant ring spectra as Tambara functors valued in ?-groupoids; this is joint work in progress with Bastiaan Cnossen, Tobias Lenz, and Sil Linskens.



Angelegt am Monday, 08.04.2024 06:13 von Claudia Rüdiger
Geändert am Monday, 08.04.2024 06:13 von Claudia Rüdiger
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Claudia Lückert

Wilhelm Killing Kolloquium: Prof. Dr. Thomas Koberda (University of Virginia): Homeomorphism groups of manifolds and first order logic

Thursday, 18.04.2024 14:15 im Raum M4

Mathematik und Informatik

Infinite groups have been studied from many perspectives, including combinatorial group theory and geometric group theory. Non-locally compact groups such as homeomorphism groups of manifolds resist classical techniques. I will discuss some recent methods for investigating groups of homeomorphisms, and indicate applications to geometric group theory and dynamics.



Angelegt am Monday, 04.03.2024 10:40 von Claudia Lückert
Geändert am Friday, 12.04.2024 06:52 von Claudia Lückert
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Kolloquium Wilhelm Killing
Vorträge des SFB 1442
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Heike Harenbrock

Mittagsseminar zur Arithmetik: Felix Schremmer (Hong Kong): Beyond minute admissible sets

Tuesday, 23.04.2024 10:15 im Raum SRZ 216/217

Mathematik und Informatik

If a Shimura variety is fully Hodge-Newton decomposable, its mod p reduction enjoys particularly nice properties. These cases are well-understood and characterized by a certain inequality known as the minute condition. In a joint project with Xuhua He and Eva Viehmann, we study the next larger cases, where the minute condition is barely not satisfied any more. I will give a classification of these cases and explain the geometric properties of the corresponding Ekedahl-Oort and Kottwitz-Rapoport strata. The Ekedahl-Oort strata are described by a new class of affine Deligne-Lusztig varieties introduced in a joint work with Ryosuke Shimada and Qingchao Yu. For these affine Deligne-Lusztig varieties of positive Coxter type, we give a full description of their dimensions and the sets of irreducible components.



Angelegt am Monday, 08.04.2024 10:06 von Heike Harenbrock
Geändert am Monday, 08.04.2024 10:06 von Heike Harenbrock
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Elke Enning

Aaron Tikuisis (z.Z. Oxford): Central sequences and topological dynamics. Oberseminar C*-Algebren.

Tuesday, 23.04.2024 16:15 im Raum SRZ 216/217

Mathematik und Informatik

Central sequences play a fundamental role in operator algebras, from property Gamma and the MacDuff property for II_1 factors to characterizations of tensorial absorption for C*-algebras, for example. Given the deep link between operator algebras and dynamics, it is natural to look for dynamical analogues of central sequence properties. This turns out to be subtle. In joint work with Grigorios Kopsacheilis, Hung-Chang Liao, and Andrea Vaccaro, a central sequence property (uniform property Gamma) is shown to be equivalent to a topological dynamical property (the small boundary property). I will discuss a body of work related to these ideas.



Angelegt am Thursday, 04.04.2024 07:55 von Elke Enning
Geändert am Thursday, 11.04.2024 06:37 von Elke Enning
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Oberseminare und sonstige Vorträge
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Claudia Rüdiger

Alexis Aumonier (University of Cambridge): Stable cohomology of moduli of smooth hypersurfaces

Wednesday, 24.04.2024 16:30 im Raum M4

Mathematik und Informatik

Abstract: The space of all smooth hypersurfaces of a given degree in a complex projective variety is itself a variety. I will explain how to understand some of its cohomology using tools from homotopy theory: smooth hypersurfaces are given by holomorphic sections of line bundles subject to a differential condition, and these can be compared to continuous sections of appropriate jet bundles. This strategy usually goes under the name of "h-principle", and we will see an algebraic instance of that. I will also explain some consequences: a cohomological stability phenomenon, and a relation to classifying spaces of diffeomorphism groups of hypersurfaces.



Angelegt am Wednesday, 10.04.2024 11:00 von Claudia Rüdiger
Geändert am Wednesday, 10.04.2024 11:00 von Claudia Rüdiger
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