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A note on total domination in 5-regular graphs

LI Shan1  SHAN Erfang2,*  ZHANG Lin1   

  1. 1. Department of Mathematics,   Shanghai University,  Shanghai 200444,  China; 2. School of Management,   Shanghai University, Shanghai 200444,  China
  • Received:2016-07-24 Online:2017-03-15 Published:2017-03-15

Abstract:

Let G be a graph without isolated vertices. A total dominating set of G is a subset S of V(G) such that every vertex of G is adjacent to a vertex in S. The minimum cardinality of a total dominating set of G is denoted by \gamma_t(G). Recently, Thomass\'e and Yeo showed that \gamma_t(G)\le 17n/44 for a connected graph G of order n with minimum degree at least five. In this paper we prove that \gamma_t(G)\le 106n/275 for a 5-regular graph G of order n, which improves sightly the bound of Thomass\'e and Yeo.

Key words: total domination, regular graph, hypergraph, bound