Ramanujan Cayley graphs on sporadic groups

Let \Gamma be a k-regular graph with the second maximum  eigenvalue \lambda. Then  \Gamma is said o be Ramanujan graph if \lambda\leq ۲\sqrt{k-۱}. Let G be a finite group  and \Gamma=Cay(G,S) be a Cayley graph related to G.  The aim of this paper is to investigate the Ramanujan Cayley graphs of sporadic groups.

کلیدواژه ها:

sporadic group ، character table ، Cayley graph ، eigenvalue