Domination in Graphs of Minimum Degree at least Two and Large Girth

  • Authors:
  • Christian Löwenstein;Dieter Rautenbach

  • Affiliations:
  • TU Ilmenau, Institut für Mathematik, Postfach 100565, D-98684, Ilmenau, Germany;TU Ilmenau, Institut für Mathematik, Postfach 100565, D-98684, Ilmenau, Germany

  • Venue:
  • Graphs and Combinatorics
  • Year:
  • 2008

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Abstract

We prove that for graphs of order n, minimum degree δ ≥ 2 and girth g ≥ 5 the domination number γ satisfies $$\gamma\leq\left(\frac{1}{3}+\frac{2}{3g}\right)n$$. As a corollary this implies that for cubic graphs of order n and girth g ≥ 5 the domination number γ satisfies $$\gamma \leq \left(\frac{44}{135}+\frac{82}{135g}\right)n$$ which improves recent results due to Kostochka and Stodolsky (An upper bound on the domination number of n-vertex connected cubic graphs, manuscript (2005)) and Kawarabayashi, Plummer and Saito (Domination in a graph with a 2-factor, J. Graph Theory 52 (2006), 1–6) for large enough girth. Furthermore, it confirms a conjecture due to Reed about connected cubic graphs (Paths, stars and the number three, Combin. Prob. Comput. 5 (1996), 267–276) for girth at least 83.