Competitive analysis of maintaining frequent items of a stream

  • Authors:
  • Yiannis Giannakopoulos;Elias Koutsoupias

  • Affiliations:
  • Department of Informatics, University of Athens, Greece;Department of Informatics, University of Athens, Greece

  • Venue:
  • SWAT'12 Proceedings of the 13th Scandinavian conference on Algorithm Theory
  • Year:
  • 2012

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Abstract

We study the well-known frequent items problem in data streams from a competitive analysis point of view. We consider the standard worst-case input model, as well as a weaker distributional adversarial setting. We are primarily interested in the single-slot memory case and for both models we give (asymptotically) tight bounds of $\varTheta(\sqrt{N})$ and $\varTheta(\sqrt[3]{N})$ respectively, achieved by very simple and natural algorithms, where N is the stream's length. We also provide lower bounds, for both models, in the more general case of arbitrary memory sizes of k≥1.