Daniel Studenmund, Binghamton University
Event Date
2025-04-23
Event Time
02:30 pm ~ 03:30 pm
Event Location
Wachman 617
Abstract: Symmetries of a group $G$ are encoded in the automorphism group $Aut(G)$. "Hidden symmetries" are encoded in the abstract commensurator $Comm(G)$. While many classes of finitely generated groups have reasonably well-understood commensurator -- for example, when $G$ is an arithmetic group, $Comm(G)$ is typically a group of matrices with rational entries -- the abstract commensurator of a free group, $Comm(F_2)$, is still somewhat mysterious. I will explain how Edgar A. Bering IV and I fleshed out a topological perspective of commensurations that allowed us to show that every countable locally finite group is a subgroup of $Comm(F_2)$.