Distributed weighted vertex cover via maximal matchings

  • Authors:
  • Fabrizio Grandoni;Jochen Könemann;Alessandro Panconesi

  • Affiliations:
  • Università di Roma Tor Vergata, Roma, Italy;University of Waterloo, Waterloo, ON, Canada;Sapienza Università di Roma, Roma, Italy

  • Venue:
  • ACM Transactions on Algorithms (TALG)
  • Year:
  • 2008

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Abstract

In this article, we consider the problem of computing a minimum-weight vertex-cover in an n-node, weighted, undirected graph G = (V,E). We present a fully distributed algorithm for computing vertex covers of weight at most twice the optimum, in the case of integer weights. Our algorithm runs in an expected number of O(log n + log Ŵ) communication rounds, where Ŵ is the average vertex-weight. The previous best algorithm for this problem requires O(log n(log n + logŴ)) rounds and it is not fully distributed. For a maximal matching M in G, it is a well-known fact that any vertex-cover in G needs to have at least |M| vertices. Our algorithm is based on a generalization of this combinatorial lower-bound to the weighted setting.