Oriented bicyclic graphs whose skew spectral radius does not exceed 2

Abstract

Let S(G σ ) be the skew-adjacency matrix of the oriented graph G σ of order n and λ 1 , λ 2 , · · · , λ n be all eigenvalues of S(G σ ). The skew-spectral radius ρ s (G σ ) of G σ is defined as max{|λ 1 |, |λ 2 |, · · · , |λ n |}. In this paper, we investigate oriented bicyclic graphs whose skew-spectral radius does not exceed 2.