Lower bounds for on-line graph coloring

  • Authors:
  • Magnús M. Halldórsson;Márió Szegedy

  • Affiliations:
  • -;-

  • Venue:
  • SODA '92 Proceedings of the third annual ACM-SIAM symposium on Discrete algorithms
  • Year:
  • 1992

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Abstract

An algorithm for vertex-coloring graphs is said to be online if each vertex is irrevocably assigned a color before any later vertices are considered. We show that such algorithms are inherently ineffective. The performance ratio of any such algorithm can be no better than &OHgr;(n/log2 n), even for randomized algorithms against oblivious adversary.We also show that various means of relaxing the constraints of the on-line model do not reduce these lower bounds. The features include presenting the input in blocks of log2 n vertices, recoloring any fraction of the vertices, presorting vertices according to degree, and disclosing the adversary's previous coloring.