Maximum number of colors in hypertrees of bounded degree

Csilla Bujtás, Z. Tuza

Research output: Contribution to journalArticle


The upper chromatic number (Formula presented.) of a hypergraph (Formula presented.) is the maximum number of colors that can occur in a vertex coloring φ:X→N such that no edge E∈E is completely multicolored. A hypertree (also called arboreal hypergraph) is a hypergraph whose edges induce subtrees on a fixed tree graph. It has been shown that on hypertrees it is algorithmically hard not only to determine exactly but also to approximate the value of χ¯, unless P=NP. In sharp contrast to this, here we prove that if the input is restricted to hypertrees H of bounded maximum vertex degree, then χ¯(H) can be determined in linear time if an underlying tree is also given in the input. Consequently, χ¯ on hypertrees is fixed parameter tractable in terms of maximum degree.

Original languageEnglish
Pages (from-to)867-876
Number of pages10
JournalCentral European Journal of Operations Research
Issue number4
Publication statusPublished - Dec 1 2015



  • Arboreal hypergraph
  • C-coloring
  • Hypergraph
  • Hypertree
  • Upper chromatic number
  • Vertex coloring

ASJC Scopus subject areas

  • Management Science and Operations Research

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