Abstract
A 2-rainbow domination function of a graph G is a function f that assigns to each vertex a set of colors chosen from the set {1, 2}, such that for any \({v\in V(G), f(v)=\emptyset}\) implies \({\bigcup_{u\in N(v)}f(u)=\{1,2\}.}\) The 2-rainbow domination number γ r2(G) of a graph G is the minimum \({w(f)=\Sigma_{v\in V}|f(v)|}\) over all such functions f. Let G be a connected graph of order |V(G)| = n ≥ 3. We prove that γ r2(G) ≤ 3n/4 and we characterize the graphs achieving equality. We also prove a lower bound for 2-rainbow domination number of a tree using its domination number. Some other lower and upper bounds of γ r2(G) in terms of diameter are also given.
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The work is supported by NSFC under Grant No. 11126054.
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Wu, Y., Rad, N.J. Bounds on the 2-Rainbow Domination Number of Graphs. Graphs and Combinatorics 29, 1125–1133 (2013). https://doi.org/10.1007/s00373-012-1158-y
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DOI: https://doi.org/10.1007/s00373-012-1158-y