$O(\sqrt{\logn})$ Approximation to SPARSEST CUT in $\tilde{O}(n^2)$ Time

  • Authors:
  • Sanjeev Arora;Elad Hazan;Satyen Kale

  • Affiliations:
  • arora@cs.princeton.edu;hazan@us.ibm.com;skale@yahoo-inc.com

  • Venue:
  • SIAM Journal on Computing
  • Year:
  • 2010

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Abstract

This paper shows how to compute $O(\sqrt{\log n})$-approximations to the Sparsest Cut and Balanced Separator problems in $\tilde{O}(n^2)$ time, thus improving upon the recent algorithm of Arora, Rao, and Vazirani [Proceedings of the 36th Annual ACM Symposium on Theory of Computing, 2004, pp. 222-231]. Their algorithm uses semidefinite programming and requires $\tilde{O}(n^{9.5})$ time. Our algorithm relies on efficiently finding expander flows in the graph and does not solve semidefinite programs. The existence of expander flows was also established by Arora, Rao, and Vazirani [Proceedings of the 36th Annual ACM Symposium on Theory of Computing, 2004, pp. 222-231].