科研之友
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摘要
A vertex of a graph is said to dominate itself and all of its neighbors. A double outer-independent dominating set of a graph G is a set D of vertices of G such that every vertex of G is dominated by at least two vertices of D, and the set V (G) \ D is independent. The double outer-independent domination number of a graph G, denoted by a gamma(oi)(d) (G), is the minimum cardinality of a double outer-independent dominating set of G. We prove that for every nontrivial tree T of order n, with l leaves and s support vertices we have a gamma(oi)(d) (T) <= (2n + l + s)/3, and we characterize the trees attaining this upper bound.
- 出版日期2015-3
