Approximation schemes for minimum 2-connected spanning subgraphs in weighted planar graphs

  • Authors:
  • André Berger;Artur Czumaj;Michelangelo Grigni;Hairong Zhao

  • Affiliations:
  • Department of Mathematics and Computer Science, Emory University, Atlanta, GA;Department of Computer Science, New Jersey Institute of Technology, Newark, NJ;Department of Mathematics and Computer Science, Emory University, Atlanta, GA;Department of Computer Science, New Jersey Institute of Technology, Newark, NJ

  • Venue:
  • ESA'05 Proceedings of the 13th annual European conference on Algorithms
  • Year:
  • 2005

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Abstract

We present new approximation schemes for various classical problems of finding the minimum-weight spanning subgraph in edge-weighted undirected planar graphs that are resistant to edge or vertex removal. We first give a PTAS for the problem of finding minimum-weight 2-edge-connected spanning subgraphs where duplicate edges are allowed. Then we present a new greedy spanner construction for edge-weighted planar graphs, which augments any connected subgraph A of a weighted planar graph G to a (1+ε)-spanner of G with total weight bounded by weight(A)/ε. From this we derive quasi-polynomial time approximation schemes for the problems of finding the minimum-weight 2-edge-connected or biconnected spanning subgraph in planar graphs. We also design approximation schemes for the minimum-weight 1-2-connectivity problem, which is the variant of the survivable network design problem where vertices have 1 or 2 connectivity constraints. Prior to our work, for all these problems no polynomial or quasi-polynomial time algorithms were known to achieve an approximation ratio better than 2.