A Roman dominating function on a graph G = （V, E） is a function f ： V→{0, 1, 2} satisfying the condition that every vertex u for which f（u） = 0 is adjacent to at least one vertex v for which f（v） = 2. The weig...A Roman dominating function on a graph G = （V, E） is a function f ： V→{0, 1, 2} satisfying the condition that every vertex u for which f（u） = 0 is adjacent to at least one vertex v for which f（v） = 2. The weight of a Roman dominating function is the value f（V） = Σu∈Vf（u）. The minimum weight of a Roman dominating function on a graph G, denoted by γR（G）, is called the Roman dominating number of G. In this paper, we will characterize a tree T with γR（T） = γ（T） ＋ 3.展开更多
基金Supported by the NSF of education Department of Henan Province(200510475038)
文摘A Roman dominating function on a graph G = （V, E） is a function f ： V→{0, 1, 2} satisfying the condition that every vertex u for which f（u） = 0 is adjacent to at least one vertex v for which f（v） = 2. The weight of a Roman dominating function is the value f（V） = Σu∈Vf（u）. The minimum weight of a Roman dominating function on a graph G, denoted by γR（G）, is called the Roman dominating number of G. In this paper, we will characterize a tree T with γR（T） = γ（T） ＋ 3.
