# Ramanujan Complexes of any Affine Type

 COMPUTER SCIENCE/DISCRETE MATH 1 Topic: Ramanujan Complexes of any Affine Type Speaker: Donald Cartwright Affiliation: University of Sydney Date: Tuesday, December 20 Time/Room: 10:30am - 12:30pm/S-101

Ramanujan complexes of type ${\tilde A}_n$ have been constructed by Lubotzky, Samuels and Vishne. In this talk I would like to propose a definition of Ramanujan complexes associated with buildings of any affine type. This involves defining appropriate adjacency operators, studying their properties such as commutativity and describing their joint spectrum.