文摘
Let k≥1k≥1 be an integer, and let GG be a graph. A kk-rainbow dominating function (or a kk-RDF ) of GG is a function ff from the vertex set V(G)V(G) to the family of all subsets of {1,2,…,k}{1,2,…,k} such that for every v∈V(G)v∈V(G) with f(v)=0̸f(v)=0̸, the condition ⋃u∈NG(v)f(u)={1,2,…,k}⋃u∈NG(v)f(u)={1,2,…,k} is fulfilled, where NG(v)NG(v) is the open neighborhood of vv. The weight of a kk-RDF ff of GG is the value ω(f)=∑v∈V(G)∣f(v)∣ω(f)=∑v∈V(G)∣f(v)∣. The kk-rainbow domination number of GG, denoted by γrk(G)γrk(G), is the minimum weight of a kk-RDF of GG. The 11-rainbow domination is the same as the classical domination.The kk-rainbow reinforcement number of GG, denoted by rrk(G)rrk(G), is the minimum number of edges that must be added to GG in order to decrease the kk-rainbow domination number. In this paper, we study the kk-rainbow reinforcement number of graphs to compare γrkγrk and γrk′γrk′ for k≠k′k≠k′, and present some sharp bounds concerning the invariant.