When:
Thursday, October 30, 2025
4:00 PM - 5:00 PM CT
Where: Lunt Hall, 105, 2033 Sheridan Road, Evanston, IL 60208 map it
Audience: Faculty/Staff - Student - Post Docs/Docs - Graduate Students
Contact:
Antonio Auffinger
(847) 491-5524
tuca@northwestern.edu
Group: Department of Mathematics: Special Events
Category: Lectures & Meetings
Title: Topological expanders
Abstract: Gromov's overlapping problems led to the notions of geometric and topological expanders. These problems have been solved by using the high-dimensional expanders ( a.k.a. Ramanujan complexes). We will survey these developments, Then we will point out how the methods developed there MAY be useful to tackle the holy grail open problem of group approximation theory: are all groups sofic? Based on joint works with Kaufman, Kazhdan, Evra, Chapman, and Dikstein.