Topology and Group Theory Seminar: January 29, 2025

Jan. 29, 2025—Speaker: Abdul Zalloum (University of Toronto) Title: From coarse to fine: a generalized Sageev’s construction in hyperbolic spaces Abstract: I will discuss a construction that starts with a set S, a collection of bi-partitions on S called walls, and produces a spectrum of metric spaces, including Helly graphs, hyperbolic spaces, and injective metric spaces. The resulting space depends on the combinatorics of the walls; for example, if pairs...

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Topology and Group Theory Seminar: January 22, 2025

Jan. 22, 2025—Speaker: Mike Mihalik (Vanderbilt) Title: Stallings’ group is simply connected at infinity Abstract: For n ≥ 2, let Bn denote the kernel of the homomorphism from the direct product of n-copies of the free group on two generators to the group of integers which sends all generators to the generator 1. The groups Bn are called the Bieri-Stallings groups and Bn is of type Fn-1 but not Fn. Classical...

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