Approximation algorithms for the bottleneck stretch factor problem

  • Authors:
  • Giri Narasimhan;Michiel Smid

  • Affiliations:
  • School of Computer Science, Florida International University Miami, FL;School of Computer Science, Carleton University Ottawa, Ontario, Canada K1S 5B6

  • Venue:
  • Nordic Journal of Computing
  • Year:
  • 2002

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Abstract

The stretch factor of a Euclidean graph is the maximum ratio of the distance in the graph between any two points and their Euclidean distance. The following problem is considered. Preprocess a set S of n points in Rd into a data structure that supports the following queries: Given an arbitrary query value b 0, compute a constant-factor approximation of the stretch factor of the graph Gb, which is the graph on S containing all edges of length at most b. We give a data structure for this problem having size O(log n) and query time O(log log n). Even though there could be up to (n 2) different stretch factors in the collection {Gb : b 0} of graphs, we show that this data structure can be constructed in subquadratic time.Our algorithms use techniques from computational geometry, such as minimum spanning trees, well-separated pairs, data structures for the nearest-neighbor problem, and algorithms for selecting and ranking distances.