Geometric optimization problems over sliding windows

  • Authors:
  • Timothy M. Chan;Bashir S. Sadjad

  • Affiliations:
  • School of Computer Science, University of Waterloo, Waterloo, Ontario, Canada;School of Computer Science, University of Waterloo, Waterloo, Ontario, Canada

  • Venue:
  • ISAAC'04 Proceedings of the 15th international conference on Algorithms and Computation
  • Year:
  • 2004

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Abstract

We study the problem of maintaining a (1+ε)-factor approximation of the diameter of a stream of points under the sliding window model In one dimension, we give a simple algorithm that only needs to store $O(\frac{1}{\epsilon}{\rm log}R)$ points at any time, where the parameter R denotes the “spread” of the point set This bound is optimal and improves Feigenbaum, Kannan, and Zhang's recent solution by two logarithmic factors We then extend our one-dimensional algorithm to higher constant dimensions and, at the same time, correct an error in the previous solution In high nonconstant dimensions, we also observe a constant-factor approximation algorithm that requires sublinear space Related optimization problems, such as the width, are also considered in the two-dimensional case.