Online conflict-free colorings for hypergraphs

  • Authors:
  • Amotz Bar-Noy;Panagiotis Cheilaris;Svetlana Olonetsky;Shakhar Smorodinsky

  • Affiliations:
  • Brooklyn College;Brooklyn College and The Graduate Center, City University of New York and School of ECE, National Technical University of Athens;Tel-Aviv University;Courant Institute, New York University

  • Venue:
  • ICALP'07 Proceedings of the 34th international conference on Automata, Languages and Programming
  • Year:
  • 2007

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Abstract

We provide a framework for online conflict-free coloring (CFcoloring) of any hypergraph. We use this framework to obtain an efficient randomized online algorithm for CF-coloring any k-degenerate hypergraph. Our algorithm uses O(k log n) colors with high probability and this bound is asymptotically optimal for any constant k. Moreover, our algorithm uses O(k log k log n) random bits with high probability. As a corollary, we obtain asymptotically optimal randomized algorithms for online CF-coloring some hypergraphs that arise in geometry. Our algorithm uses exponentially fewer random bits compared to previous results. We introduce deterministic online CF-coloring algorithms for points on the line with respect to intervals and for points on the plane with respect to halfplanes (or unit discs) that use Θ(log n) colors and recolor O(n) points in total.