Toughness and spectrum of a graph
The author proves the following theorem: Let \(G\) be a connected non- complete regular graph of valency \(d\) and let \(\lambda\) be the maximum of the absolute values of the eigenvalues of \(G\) distinct from \(d\). Then the toughness \(t\) of \(G\) satisfies \(t> d/\lambda- 2\).
scientific article; zbMATH DE number 803741