On the diameter of the Kronecker product graph

Let G₁ and G₂ be two undirected nontrivial graphs. The Kronecker product of G₁ and G₂ denoted by G₁⊗ G₂ with vertex set V(G₁)× V(G₂), two vertices x₁x₂ and y₁y₂ are adjacent if and only if (x₁,y₁)∈ E(G₁) and (x₂,y₂)∈ E(G₂). This paper presents a formula for computing the diameter of G₁⊗ G₂ by means of the diameters and primitive exponents of factor graphs.