Abstract
In this paper we study isomorphisms of some covers of a symmetric digraph. Let D be a symmetric digraph, Γ a group of automorphisms of D and A a finite group. We present a characterization for two cyclic A-covers of D to be Γ-isomorpihic. Furthermore, in the case that A is the r-dimensional vector space F^r_p over the finite field F_p with p(>2) elements, we discuss the number of Γ-isomorphism classes of cycilc F^r_p-covers of D. Finally, we treat the enumeration and the structure of Γ-isomorphism classes of nonzero-cyclic F^r_p-covers of D.
