Almost-tight hardness of directed congestion minimization

  • Authors:
  • Matthew Andrews;Lisa Zhang

  • Affiliations:
  • Bell Labs, Murray Hill, New Jersey;Bell Labs, Murray Hill, New Jersey

  • Venue:
  • Journal of the ACM (JACM)
  • Year:
  • 2008

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Abstract

Given a set of demands in a directed graph, the directed congestion minimization problem is to route every demand with the objective of minimizing the heaviest load over all edges. We show that for any constant ϵ 0, there is no Ω(log1−ϵ M)-approximation algorithm on networks of size M unless NP ⊆ ZPTIME(npolylog n). This bound is almost tight given the O(log M/log log M)-approximation via randomized rounding due to Raghavan and Thompson.