Perfect Resolution of Conflict-Free Colouring of Interval Hypergraphs

Authors S. M. Dhannya, N. S. Narayanaswamy

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S. M. Dhannya
  • Dept. of Computer Science and Engineering, IIT Madras, Chennai, India
N. S. Narayanaswamy
  • Dept. of Computer Science and Engineering, IIT Madras, Chennai, India


We thank the anonymous reviewers for their comments which have greatly improved the quality of the paper.

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S. M. Dhannya and N. S. Narayanaswamy. Perfect Resolution of Conflict-Free Colouring of Interval Hypergraphs. In 37th International Symposium on Theoretical Aspects of Computer Science (STACS 2020). Leibniz International Proceedings in Informatics (LIPIcs), Volume 154, pp. 52:1-52:16, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2020)


Given a hypergraph H, the conflict-free colouring problem is to colour vertices of H using minimum colours so that in every hyperedge e of H, there is a vertex whose colour is different from that of all other vertices in e. Our results are on a variant of the conflict-free colouring problem considered by Cheilaris et al.[Cheilaris et al., 2014], known as the 1-Strong Conflict-Free (1-SCF) colouring problem, for which they presented a polynomial time 2-approximation algorithm for interval hypergraphs. We show that an optimum 1-SCF colouring for interval hypergraphs can be computed in polynomial time. Our results are obtained by considering a different view of conflict-free colouring which we believe could be useful in general. For interval hypergraphs, this different view brings a connection to the theory of perfect graphs which is useful in coming up with an LP formulation to select the vertices that could be coloured to obtain an optimum conflict-free colouring. The perfect graph connection again plays a crucial role in finding a minimum colouring for the vertices selected by the LP formulation.

Subject Classification

ACM Subject Classification
  • Mathematics of computing → Hypergraphs
  • Mathematics of computing → Graph algorithms
  • Theory of computation → Design and analysis of algorithms
  • Conflict-free Colouring
  • Interval Hypergraphs


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