Approximate distance oracles with improved preprocessing time

  • Authors:
  • Christian Wulff-Nilsen

  • Affiliations:
  • University of Southern Denmark

  • Venue:
  • Proceedings of the twenty-third annual ACM-SIAM symposium on Discrete Algorithms
  • Year:
  • 2012

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Abstract

Given an undirected graph G with m edges, n vertices, and non-negative edge weights, and given an integer k ≥ 1, we show that for some universal constant c, a (2k − 1)-approximate distance oracle for G of size O(kn1+1/k) can be constructed in [EQUATION] time and can answer queries in O(k) time. We also give an oracle which is faster for smaller k. Our results break the quadratic preprocessing time bound of Baswana and Kavitha for all k ≥ 6 and improve the O(kmn1/k) time bound of Thorup and Zwick except for very sparse graphs and small k. When m = [EQUATION] and k = O(1), our oracle is optimal w.r.t. both stretch, size, preprocessing time, and query time, assuming a widely believed girth conjecture by Erdős.