Adjacency Matrices of Configuration Graphs

M. Abreu, M. Funk, D. Labbate +1

In 1960, Hoffman and Singleton \cite{HS60} solved a celebrated equation for square matrices of order $n$, which can be written as $$(\kappa -1)I_n+J_n-A{A}^{\mathrm{T}}=A$$ where $I_n…