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团图为数的图中的闭团贯数
引用本文:梁作松,单而芳.团图为数的图中的闭团贯数[J].上海大学学报(英文版),2008,12(3):197-199.
作者姓名:梁作松  单而芳
作者单位:LIANG Zuo-song(Department of Mathematics, College of Sciences, Shanghai University, Shanghai 200444, P. R. China)  SHAN Er-fang(Department of Mathematics, College of Sciences, Shanghai University, Shanghai 200444, P. R. China;Department of Logistics, The Hong Kong Polytechnic University, Hong Kong, P. R. China)
基金项目:国家自然科学基金 , 上海市教委资助项目
摘    要:Given a graph G,a subgraph C is called a clique of G if C is a complete subgraph of G maximal under inclusion and |C|≥2. A clique-transversal set S of G is a set of vertices of G such that S meets all cliques of G. The clique-transversal number, denoted as TC (G), is the minimum cardinality of a clique-transversal set in G. The clique-graph of G, denoted as K (G), is the graph obtained by taking the cliques of G as vertices, and two vertices are adjacent if and only if the corresponding cliques in G have nonempty intersection. Let F be a class of graphs G such that F={G|K(G) is a tree}. In this paper the graphs in F having independent clique-transversal sets are shown and thus TC (G)/|G|≤1/2 for all G ∈ F.

关 键 词:团图    团横贯数  跳跃
收稿时间:2006-08-31
修稿时间:2006年8月31日

Clique-transversal number of graphs whose clique-graphs are trees
LIANG Zuo-song,SHAN Er-fang.Clique-transversal number of graphs whose clique-graphs are trees[J].Journal of Shanghai University(English Edition),2008,12(3):197-199.
Authors:LIANG Zuo-song  SHAN Er-fang
Affiliation:1. Department of Mathematics, College of Sciences, Shanghai University, Shanghai 200444, P. R. China
2. Department of Mathematics, College of Sciences, Shanghai University, Shanghai 200444, P. R. China;Department of Logistics, The Hong Kong Polytechnic University, Hong Kong, P. R. China
Abstract:Given a graph G,a subgraph C is called a clique of G if C is a complete subgraph of G maximal under inclusion and |C|≥2. A clique-transversal set S of G is a set of vertices of G such that S meets all cliques of G. The clique-transversal number, denoted as TC (G), is the minimum cardinality of a clique-transversal set in G. The clique-graph of G, denoted as K (G), is the graph obtained by taking the cliques of G as vertices, and two vertices are adjacent if and only if the corresponding cliques in G have nonempty intersection. Let F be a class of graphs G such that F={G|K(G) is a tree}. In this paper the graphs in F having independent clique-transversal sets are shown and thus TC (G)/|G|≤1/2 for all G ∈ F.
Keywords:clique-transversal number  clique-graph  tree  bound  团图  trees  graphs  paper  independent  sets  class  intersection  taking  minimum  cardinality  number  cliques  complete  subgraph  maximal  inclusion
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