Using expander graphs to find vertex connectivity

  • Authors:
  • Harold N. Gabow

  • Affiliations:
  • University of Colorado, Boulder, Colorado

  • Venue:
  • Journal of the ACM (JACM)
  • Year:
  • 2006

Quantified Score

Hi-index 0.00

Visualization

Abstract

The (vertex) connectivity κ of a graph is the smallest number of vertices whose deletion separates the graph or makes it trivial. We present the fastest known algorithm for finding κ. For a digraph with n vertices, m edges and connectivity κ the time bound is O((n + min{κ&frac52;, κn¾})m). This improves the previous best bound of O((n + min{κ3, κn&rcub)m). For an undirected graph both of these bounds hold with m replaced by κn. Expander graphs are useful for solving the following subproblem that arises in connectivity computation: A known set R of vertices contains two large but unknown subsets that are separated by some unknown set S of κ vertices; we must find two vertices of R that are separated by S.