Classification of smooth actions by higher rank lattices in critical dimensions

Wed Oct 26, 2022 4:15 p.m.—5:15 p.m.
Exterior of Sheffield-Sterling-Strathcona Hall featuring a stone carving of Yale's coat of arms and motto

This event has passed.

Seminar: 
Colloquium

Event time: 
Wednesday, October 26, 2022 - 4:15pm

Location: 
LOM 214

Speaker: 
Zhiren Wang

Speaker affiliation: 
Penn. State and IAS

Event description: 
The Zimmer program asks how lattices in higher rank semisimple Lie groups may act smoothly on compact manifolds. Below a certain critical dimension, the recent proof of the Zimmer conjecture by Brown-Fisher-Hurtado asserts that, for SL(n,R) with n >= 3 or other higher rank R-split semisimple Lie groups, the action is trivial up to a finite group action. In this talk, we will explain what happens in the critical dimension for higher rank R-split semisimple Lie groups. For example, non-trivial actions by lattices in SL(n,R), n >= 3, on (n-1)-dimensional manifolds are isomorphic to the standard action on RP^{n-1} up to a finite quotient group and a finite covering. This is a joint work with Aaron Brown and Federico Rodriguez Hertz.