Spring 2017

Ramanujan Covers

Monday, January 30th, 2017 2:55 pm3:40 pm

Add to Calendar

The breakthrough work of Marcus, Spielman, and Srivastava showed that every bipartite Ramanujan graph has a bipartite Ramanujan double cover. Chris Hall, Doron Puder, and I generalized this to covers of arbitrary degree. I will explain the proof, with emphasis on how group theory and representation theory are useful for this problem.