Characterization of trees with equal 2-domination number and domination number plus two
نویسندگان
چکیده
Let G = (V (G), E(G)) be a simple graph, and let k be a positive integer. A subset D of V (G) is a k-dominating set if every vertex of V (G) − D is dominated at least k times by D. The k-domination number γk(G) is the minimum cardinality of a k-dominating set of G. In [5] Volkmann showed that for every nontrivial tree T, γ2(T ) ≥ γ1(T ) + 1 and characterized extremal trees attaining this bound. In this paper we characterize all trees T with γ2(T ) = γ1(T ) + 2.
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عنوان ژورنال:
- Discussiones Mathematicae Graph Theory
دوره 31 شماره
صفحات -
تاریخ انتشار 2011