A (slightly) faster algorithm for klee's measure problem

  • Authors:
  • Timothy M. Chan

  • Affiliations:
  • University of Waterloo, Waterloo, ON, Canada

  • Venue:
  • Proceedings of the twenty-fourth annual symposium on Computational geometry
  • Year:
  • 2008

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Abstract

Given n axis-parallel boxes in a fixed dimension d ≥ 3, how efficiently can we compute the volume of the union? This standard problem in computational geometry, commonly referred to as Klee's measure problem, can be solved in time O(nd/2 log n) by an algorithm of Overmars and Yap (FOCS 1988). We give the first (albeit small) improvement: our new algorithm runs in time nd/22O(log*n), where log* denotes the iterated logarithm. For the related problem of computing the depth in an arrangement of n boxes, we further improve the time bound to near O(nd/2 logd/2-1 n), ignoring log\log n factors. Other applications and lower-bound possibilities are discussed. The ideas behind the improved algorithms are simple.