Approximate Coloring of Uniform Hypergraphs (Extended Abstract)

  • Authors:
  • Michael Krivelevich;Benny Sudakov

  • Affiliations:
  • -;-

  • Venue:
  • ESA '98 Proceedings of the 6th Annual European Symposium on Algorithms
  • Year:
  • 1998

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Abstract

We consider an algorithmic problem of coloring r-uniform hypergraphs. The problem of finding the exact value of the chromatic number of a hypergraph is known to be NP-hard, so we discuss approximate solutions to it. Using a simple construction and known results on hardness of graph coloring, we show that for any r ≥ 3 it is impossible to approximate in polynomial time the chromatic number of r-uniform hypergraphs on n vertices within a factor n1-Ɛ for any Ɛ 0, unless NP ⊆ ZPP. On the positive side, we present an approximation algorithm for coloring r-uniform hypergraphs on n vertices, whose performance ratio is O(n(log log n)2=(log n)2). We also describe an algorithm for coloring 3-uniform 2-colorable hypergraphs on n vertices in Õ (n9/41) colors, thus improving previous results of Chen and Frieze and of Kelsen, Mahajan and Ramesh.