NOTE ON SKEW-EIGENVALUES OF DIGRAPHS.

Let Gσ be an oriented graph with underlying simple graph G. The skew-adjacency matrix of Gσ is the {0, 1,-1}-matrix S = S(Gσ) = [sij ], such that sij = 1 if (vi, vj) is an arc in Gσ, sij = -1 if (vj, vi) is an arc in Gσ and sij = 0, otherwise. In this paper, all connected oriented graphs with three distinct skew-eigenvalues 0 and ±2i are characterized. [ABSTRACT FROM AUTHOR]