Maximum degree in graphs of diameter 2
Paul L. Erdos, Siemion Fajtlowicz, Alan J. Hoffman · Networks · 1980
Abstract It is well known that there are at most four Moore graphs of diameter 2, i.e., graphs of diameter 2, maximum degree d , and d 2 + 1 vertices. The purpose of this paper is to prove that with the exception of C 4 , there are no graphs of diameter 2, of maximum degree d , and with d 2 vertices.