# Ramanujan Graphs (VII)

#### by Sanming Zhou

Institution: The University of Melbourne
Date: Wed 20th March 2013
Time: 11:00 AM
Location: Room 107, Richard Berry

Abstract: The Ramanujan graphs $X^{p, q}$ of Lubotzky, Phillips and Sarnak can be defined as Cayley graphs on $PSL_{2}(q)$ or $PGL_{2}(q)$. In this week we will discuss basic properties of these groups with an emphasis on the structure of subgroups of $PSL_{2}(q)$.