Algorithmic aspects of k-tuple total domination in graphs

Abstract

For a fixed positive integer k, a k-tuple total dominating set of a graph G=(V,E) is a subset TDk of V such that every vertex in V is adjacent to at least k vertices of TDk. In minimum k-tuple total dominating set problem (Mink-Tuple Total Dom Set), it is required to find a k-tuple total dominating set of minimum cardinality and Decide Mink-Tuple Total Dom Set is the decision version of Mink-Tuple Total Dom Set problem. In this paper, we show that Decide Mink-Tuple Total Dom Set is NP-complete for split graphs, doubly chordal graphs and bipartite graphs. For chordal bipartite graphs, we show that Mink-Tuple Total Dom Set can be solved in polynomial time. We also propose some hardness results and approximation algorithms for Mink-Tuple Total Dom Set problem.