Dichromatic Polynomial of Product Digraphs

A k  -colouring of a digraph D=(V,A)D=(V,A) is a partition of V(D)V(D) into k acyclic sets. The minimum integer k for which there exists a k-colouring of D   is the dichromatic number χd(D)χd(D) of the digraph D. In this paper, we obtain dichromatic polynomial of product digraphs.