Theory of Computing Systems

, Volume 56, Issue 1, pp 22–40 | Cite as

OnlineMin: A Fast Strongly Competitive Randomized Paging Algorithm

  • Gerth Stølting Brodal
  • Gabriel MoruzEmail author
  • Andrei Negoescu


In the field of online algorithms paging is one of the most studied problems. For randomized paging algorithms a tight bound of H k on the competitive ratio has been known for decades, yet existing algorithms matching this bound have high running times. We present a new randomized paging algorithm OnlineMin that has optimal competitiveness and allows fast implementations. In fact, if k pages fit in internal memory the best previous solution required O(k 2) time per request and O(k) space. We present two implementations of OnlineMin which use O(k) space, but only O(logk) worst case time and O(logk/loglogk) worst case time per page request respectively.


On-line algorithms Competitive analysis Paging Randomized algorithms 



We would like to thank previous anonymous reviewers for very insightful comments and suggestions. Also, we would like to thank Annamária Kovács for useful advice on improving the presentation of the paper.


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Copyright information

© Springer Science+Business Media New York 2012

Authors and Affiliations

  • Gerth Stølting Brodal
    • 1
  • Gabriel Moruz
    • 2
    Email author
  • Andrei Negoescu
    • 2
  1. 1.MADALGO (Center for Massive Data Algorithmics, a Center of the Danish National Research Foundation), Department of Computer ScienceAarhus UniversityAarhus NDenmark
  2. 2.Institut für InformatikGoethe-Universität Frankfurt am MainFrankfurt am MainGermany

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