An algorithm to evaluate the spectral expansion

Hau-Wen Huang

Assume that $X$ is a connected $(q+1)$-regular undirected graph of finite order $n$. Let $A$ denote the adjacency matrix of $X$. Let ${\lambda }_1=q+1>{\lambda }_2\ge {\lambda }_3\ge \dots \ge {\lambda }_n$ denot…