We study nonregular graphs with three eigenvalues.We determine all the ones with least eigenvalue -2, and give new …

For most feasible spectra of connected regular graphs with four distinct eigenvalues and at most 30 vertices we find … all such graphs, using both theoretic and computer results. …

In this paper, we begin the determination of all primitive strongly regular graphs with chromatic number equal to 5 … set, we must decide which strongly regular graphs, if any, possessing the set are 5-chromatic.In this way, we deal …