摘要

A no-hole 2-distant coloring of a graph Gamma is an assignment c of nonnegative integers to the vertices of Gamma such that vertical bar c(v) - c(w)vertical bar >= 2 for any two adjacent vertices v and w, and the integers used are consecutive. Whenever such a coloring exists, define nsp(Gamma) to be the minimum difference (over all c) between the largest and smallest integers used. In this paper we study the no-hole 2-distant coloring problem for Cayley graphs over finitely generated abelian groups. We give sufficient conditions for the existence of no-hole 2-distant colorings of such graphs, and obtain upper bounds for the minimum span nsp(Gamma) by using a group-theoretic approach.