Finding frequent items over sliding windows with constant update time

  • Authors:
  • Regant Y. S. Hung;Lap-Kei Lee;H. F. Ting

  • Affiliations:
  • Department of Computer Science, The University of Hong Kong, Hong Kong;Department of Computer Science, The University of Hong Kong, Hong Kong;Department of Computer Science, The University of Hong Kong, Hong Kong

  • Venue:
  • Information Processing Letters
  • Year:
  • 2010

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Abstract

In this paper, we consider the problem of finding @e-approximate frequent items over a sliding window of size N. A recent work by Lee and Ting (2006) [7] solves the problem by giving an algorithm that supports O(1@e) query and update time, and uses O(1@e) space. Their query time and memory usage are essentially optimal, but the update time is not. We give a new algorithm that supports O(1) update time with high probability while maintaining the query time and memory usage as O(1@e).