Super approximation

Seminar: 
Group Actions and Dynamics
Event time: 
Monday, September 14, 2015 - 12:15pm to 1:15pm
Location: 
205 LOM
Speaker: 
Alireza Salehi Golsefidy
Speaker affiliation: 
UCSD
Event description: 

Starting with a finitely generated subgroup G of GL(n,Q), strong approximation roughly indicates that (under certain algebraic conditions) the congruence closure of G can be understood via the Zariski-topology of G. Super approximation asks about a much finer question: how dense is G in its congruence closure?

In this talk, I present a uniform p-adic super approximation (of course, it will be explained what I mean by this). This result is based on a sum-product phenomenon in non-Archimedean local fields of characteristic zero.