Regular character-graphs whose eigenvalues are greater than or equal to -2

Mahdi Ebrahimi, Maryam Khatami, Zohreh Mirzaei

Let $G$ be a finite group and $\mathrm{Irr}(G)$ be the set of all complex irreducible characters of $G$. The character-graph $\Delta (G)$ associated to $G$, is a graph whose vertex set i…