An SDP primal-dual algorithm for approximating the Lovász-theta function

  • Authors:
  • T.-H. Hubert Chan;Kevin L. Chang;Rajiv Raman

  • Affiliations:
  • Max-Planck-Institut für Informatik, Saarbrücken, Germany;Yahoo Labs, Santa Clara, California;Max-Planck-Institut für Informatik, Saarbrücken, Germany

  • Venue:
  • ISIT'09 Proceedings of the 2009 IEEE international conference on Symposium on Information Theory - Volume 4
  • Year:
  • 2009

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Abstract

The Lovász Θ-function [Lov79] on a graph G = (V, E) can be defined as the maximum of the sum of the entries of a positive semidefinite matrix X, whose trace Tr(X) equals 1, and Xij = 0 whenever {i, j} ∈ E. This function appears as a subroutine for many algorithms for graph problems such as maximum independent set and maximum clique. We apply Arora and Kale's primal-dual method for SDP to design an approximate algorithm for the Θ-function with an additive error of δ 0, which runs in time O(α2n2/δ2 logn ċ Me), where α = Θ(G) and Me = O(n3) is the time for a matrix exponentiation operation. Moreover, our techniques generalize to the weighted Lovász Θ-function, and both the maximum independent set weight and the maximum clique weight for vertex weighted perfect graphs can be approximated within a factor of (1+ơ) in time O(ơ-2n5 log n).