On k-domination and minimum degree in graphs

  • Authors:
  • Odile Favaron;Adriana Hansberg;Lutz Volkmann

  • Affiliations:
  • L.R.I., CNRS URM 8623, Bât. 490, Universite Paris-Sud, Orsay F-91405, France;Lehrstuhl II Für Mathematik, Rwth Aachen University, 52056 Aachen, Germany;Lehrstuhl II Für Mathematik, Rwth Aachen University, 52056 Aachen, Germany

  • Venue:
  • Journal of Graph Theory
  • Year:
  • 2008

Quantified Score

Hi-index 0.00

Visualization

Abstract

A subset S of vertices of a graph G is k-dominating if every vertex not in S has at least k neighbors in S. The k-domination number $\gamma_k(G)$ is the minimum cardinality of a k-dominating set of G. Different upper bounds on $\gamma_{k}(G)$ are known in terms of the order n and the minimum degree $\delta$ of G. In this self-contained article, we present an Erdös-type result, from which some of these bounds follow. In particular, we improve the bound $\gamma_{k}(G) \le (2k- \delta - 1)n/(2k -\delta)$ for $(\delta +3)/2 \le k \le \delta - 1$, proved by Chen and Zhou in 1998. Furthermore, we characterize the extremal graphs in the inequality $\gamma_{k}(G) \le kn/(k +1)$, if $k \le \delta$, of Cockayne et al. This characterization generalizes that of graphs realizing $\gamma_1(G) = \gamma(G) = n/2$. © 2007 Wiley Periodicals, Inc. J Graph Theory 57: 33–40, 2008