On the Banach space valued Azuma inequality and small set isoperimetry of Alon-Roichman graphs

Abstract

We discuss the connection between the expansion of small sets in graphs, and the Schatten norms of their adjacency matrix. In conjunction with a variant of the Azuma inequality for uniformly smooth normed spaces, we deduce improved bounds on the small set isoperimetry of Abelian Alon-Roichman random Cayley graphs.