On the p-Rank of the Adjacency Matrices of Strongly Regular Graphs

AbstractLet Γ be a strongly regular graph with adjacency matrix A. Let I be the identity matrix, and J the all-1 matrix. Let p be a prime. Our aim is to study the p-rank (that is, the rank over $$\mathbb{F}_p$$ , the finite field with p elements) of the matrices M = aA + bJ + cI for integral a, b, c. This note is based on van Eijl [8].