On vertex symmetric digraphs

AbstractIt is proved that if p is a prime, k and m⩽p are positive integers, and I is a vertex symmetric diagraph of order pk or mp, then Γ has an automorphism all of whose orbits have cardinality p. Vertex symmetric graphs of order 2p such that 2p−1 is not the square of a composite integer and vertex symmetric digraphs of order pk are characterised