Finding the best shortcut in a geometric network

  • Authors:
  • Mohammad Farshi;Panos Giannopoulos;Joachim Gudmundsson

  • Affiliations:
  • TU Eindhoven, The Netherlands;Freie Universität Berlin, Germany;NICTA, Sydney, Australia

  • Venue:
  • SCG '05 Proceedings of the twenty-first annual symposium on Computational geometry
  • Year:
  • 2005

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Abstract

Given a Euclidean graph G in Rd with n vertices and m edges we consider the problem of adding a shortcut such that the stretch factor of the resulting graph is minimized. Currently, the fastest algorithm for computing the stretch factor of a Euclidean graph runs in O(mn+n2 log n) time, resulting in a trivial O(mn3+n4 log n) time algorithm for computing the optimal shortcut. First, we show that a simple modification yields the optimal solution in O(n4) time using O(n2) space. To reduce the running times we consider several approximation algorithms. Our main result is a (2+ε)-approximation algorithm with running time O(nm+n2(log n+1/ε3d)) using O(n2) space.