Total domination of graphs and small transversals of hypergraphs

  • Authors:
  • Stéphan Thomassé;Anders Yeo

  • Affiliations:
  • LIRMM, 161, rue Ada, 34392, Montpellier Cedex 5, France;University of London, Department of Computer Science Royal Holloway, 161, rue Ada, TW20 0EX, Egham Surrey, UK

  • Venue:
  • Combinatorica
  • Year:
  • 2007

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Abstract

The main result of this paper is that every 4-uniform hypergraph on n vertices and m edges has a transversal with no more than (5n + 4m)/21 vertices. In the particular case n = m, the transversal has at most 3n/7 vertices, and this bound is sharp in the complement of the Fano plane. Chvátal and McDiarmid [5] proved that every 3-uniform hypergraph with n vertices and edges has a transversal of size n/2. Two direct corollaries of these results are that every graph with minimal degree at least 3 has total domination number at most n/2 and every graph with minimal degree at least 4 has total domination number at most 3n/7. These two bounds are sharp.