Conferences - Seminars

26APR
  13:00-14:00 MA A3 30

Every action of a group on a rooted tree induces an action on the boundary of the tree. This action yields various representations of the group on spaces of functions on the boundary. In this talk we discuss the structure of such representations. After reviewing of the basic concepts, we will introduce locally 2-transitive actions ... Read more about "Groups acting on rooted trees and representations on the boundary"
By Steffen Kionke (KIT)
01MAY
  10:15-11:30 CM 1 113

It is a classical problem to recover a discrete group from various rings or algebras associated with it, such as the integral group ring (cf. the Whitehead group and the Whitehead torsion). By analogy, in an operator algebraic framework we want to recover torsion-free groups from certain topological completions of the complex group ring, such ... Read more about "Topology Seminar: C*-superrigidiity of nilpotent groups"
By Sven Raum (EPFL)
08MAY
  10:15-11:15 CM 1 113

Stratified spaces appear as natural objects in singularity theory. Goresky and MacPherson introduced intersection cohomology to extend cohomological properties of closed manifolds to stratified spaces, and it proved to be a powerful tool to study those objects. However, intersection cohomology is not homotopy invariant, rather it is invariant with respect to homotopies that "preserve" the ... Read more about "Topology Seminar: Stratified homotopy theory"
By Sylvain Douteau (Université de Picardie)
15MAY
  09:15-10:15 CM 1 113

We will recall the definition of dendroidal sets as a generalization of simplicial sets, and present the connection (Quillen equivalence) to connective spectra which gives a factorization of the so-called K-theory spectrum functor from symmetric monoidal categories to spectra. We will present a common generalization of two results of Thomason: 1) posets model all homotopy ... Read more about "Topology Seminar: Combinatorial models for stable homotopy theory"
By Matija Bašić (University of Zagreb)
01JUN
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By Ass. Prof. Patrick Rubin-Declanchy, University of Bristol    
04JUN
08JUN
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  09:00-17:00 BI A0 448

Exceptional sets play an important role in numerous branches of mathematics, for instance in measure theory, topology, harmonic and complex analysis, Banach space theory, algebraic geometry, combinatorics, probability and ergodic theory, set theory and descriptive set theory, just to mention a few. Exceptional sets describe notions of smallness from various points of view, some notable ... Read more about "Ideals and exceptional sets in Polish spaces"
18JUN
22JUN
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  09:00-17:00 BI A0 448

This is the last conference of the semester and will be of a more general nature than the earlier more specialized conferences and workshops of the program. It will cover broad aspects of descriptive set theory and its connections with other areas of mathematics. Read more about "Descriptive set theory conference"
21JUN
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  17:15-18:15 BI A0 448

Fraïssé theory is a method in classical Model Theory of producing canonical limits of certain families of finite structures. For example, the random graph is the Fraïssé limit of the family of all finite graphs. It turns out that this method can be dualized, with the dualization producing projective Fraïssé limits, and applied to the ... Read more about "Professeur Slawomir Solecki Bernoulli Lecture - Compact Spaces and Logic"
By Slawomir Solecki (Cornell University)
16JUL
27JUL
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  09:00-17:00 BI A0 448

A mix of introductory lectures and research talks on partition functions and techniques for their computation, including methods such as Markov chains, correlation decay, belief propagation and convex optimization. Read more about "Introduction to Partition Functions"
01OCT
05OCT
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  09:00-17:00 BI A0 448

The goal of this workshop is to find translations and connections between various approaches to compute partition functions and, at the same time, advance the state-of-the-art in each. Read more about "Theoretical Challenges in Partition Functions"