An improved constant for Vizing's conjecture

Abstract

For any graph $G = (V,E)$, a subset $S {\subseteq} V$ dominates $G$ if $N[S] = V$. The minimum cardinality over all such $S$ is called the domination number, written $γ(G)$. The classical conjecture of V.G. Vizing states that $γ(G{\square} H) {\ge} γ(G)γ(H)$ where ${\square}$ stands for the Cartesian product of graphs. In this paper, we apply well-known results to prove the Vizing-type inequality $γ(G{\square} H) {\ge} .5809 γ(G)γ(H)$.