English

Independent transversal domination number of a graph

Combinatorics 2017-04-21 v1

Abstract

Let G=(V,E)G=(V, E) be a graph. A set SV(G)S\subseteq V(G) is a {\it dominating set} of GG if every vertex in VSV\setminus S is adjacent to a vertex of SS. The {\it domination number} of GG, denoted by γ(G)\gamma(G), is the cardinality of a minimum dominating set of GG. Furthermore, a dominating set SS is an {\it independent transversal dominating set} of GG if it intersects every maximum independent set of GG. The {\it independent transversal domination number} of GG, denoted by γit(G)\gamma_{it}(G), is the cardinality of a minimum independent transversal dominating set of GG. In 2012, Hamid initiated the study of the independent transversal domination of graphs, and posed the following two conjectures: Conjecture 1. If GG is a non-complete connected graph on nn vertices, then γit(G)n2\gamma_{it}(G)\leq\lceil\frac{n}{2}\rceil. Conjecture 2. If G is a connected bipartite graph, then γit(G)\gamma_{it}(G) is either γ(G)\gamma(G) or γ(G)+1\gamma(G)+1. We show that Conjecture 1 is not true in general. Very recently, Conjecture 2 is partially verified to be true by Ahangar, Samodivkin, Yero. Here, we prove the full statement of Conjecture 2. In addition, we give a correct version of a theorem of Hamid. Finally, we answer a problem posed by Mart\'{i}nez, Almira, and Yero on the independent transversal total domination of a graph.

Keywords

Cite

@article{arxiv.1704.06093,
  title  = {Independent transversal domination number of a graph},
  author = {Hongting Wang and Baoyindureng Wu and Xinhui An},
  journal= {arXiv preprint arXiv:1704.06093},
  year   = {2017}
}

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9 pages