Random walks on trees and Ramanujan graphs
Tatiana Smirnova-Nagnibeda
University of Geneva
Department of Mathematics
I will discuss two instances of how random walks
on infinite trees can be used to study the Ramanujan
property for finite non-regular graphs:
1) construction of infinite trees with infinitely many finite quotients none of which is Ramanujan (joint work with A. Lubotzky);
2) algorithm which decides in finite time whether a given finite graph is Ramanujan.
