An O(log n)-competitive algorithm for online constrained forest problems

  • Authors:
  • Jiawei Qian;David P. Williamson

  • Affiliations:
  • School of Operations Research and Information Engineering, Cornell University, Ithaca, NY;School of Operations Research and Information Engineering, Cornell University, Ithaca, NY

  • Venue:
  • ICALP'11 Proceedings of the 38th international colloquim conference on Automata, languages and programming - Volume Part I
  • Year:
  • 2011

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Abstract

In the generalized Steiner tree problem, we find a minimumcost set of edges to connect a given set of source-sink pairs. In the online version of this problem, the source-sink pairs arrive over time. Agrawal, Klein, and Ravi give a 2-approximation algorithm for the offline problem; Berman and Coulston give an O(log n)-competitive algorithm for the online problem. Goemans and Williamson subsequently generalized the offline algorithm of Agrawal et al. to handle a large class of problems they called constrained forest problems, and other problems, such as the prize-collecting Steiner tree problem. In this paper, we show how to combine the ideas of Goemans and Williamson and those of Berman and Coulston to give an O(log n)-competitive algorithm for online constrained forest problems, including an online version of the prize-collecting Steiner tree problem.