Total restrained domination in trees

被引:24
作者
Hattingh, Johannes H. [1 ]
Jonck, Elizabeth [2 ]
Joubert, Ernst J. [2 ]
Plummer, Andrew R. [1 ]
机构
[1] Georgia State Univ, Dept Math & Stat, Atlanta, GA 30303 USA
[2] Univ Johannesburg, Dept Math, ZA-2006 Auckland Pk, South Africa
关键词
total restrained domination; trees;
D O I
10.1016/j.disc.2006.09.014
中图分类号
O1 [数学];
学科分类号
0701 ; 070101 ;
摘要
Let G = (V, E) be a graph. A set S subset of V is a total restrained dominating set if every vertex is adjacent to a vertex in S and every vertex of V-S is adjacent to a vertex in V-S. The total restrained domination number of G, denoted by gamma(tr)(G), is the smallest cardinality of a total restrained dominating set of G. We show that if T is a tree of order n, then gamma(tr)(T) >= [n+2/2]. Moreover, we show that if T is a tree of order n = 0 mod 4, then gamma(tr)(T)>=[n+2/2] + 1. We then constructively characterize the extremal trees T of order n achieving these lower bounds. (C) 2006 Elsevier B.V. All rights reserved.
引用
收藏
页码:1643 / 1650
页数:8
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