Buying a Constant Competitive Ratio for Paging

János Csirik, Csanád Imreh, John Noga, Steve S. Seiden, Gerhard Woeginger

Research output: Chapter in Book/Report/Conference proceedingConference contributionAcademicpeer-review

5 Citations (Scopus)
10 Downloads (Pure)


We consider a variant of the online paging problem where the online algorithm may buy additional cache slots at a certain cost. The overall cost incurred equals the total cost for the cache plus the number of page faults. This problem and our results are a generalization of both, the classical paging problem and the ski rental problem.

We derive the following three tight results: (1) For the case where the cache cost depends linearly on the cache size, we give a λ-competitive online algorithm where λ ≈ 3.14619 is a solution of λ = 2 + ln λ. This competitive ratio λ is best possible. (2) For the case where the cache cost grows like a polynomial of degree d in the cache size, we give an online algorithm whose competitive ratio behaves like d/lnd + o(d/lnd). No online algorithm can reach a competitive ratio better than d/lnd. (3) We exactly characterize the class of cache cost functions for which there exist online algorithms with finite competitive ratios.
Original languageEnglish
Title of host publicationAlgorithms — ESA 2001
Subtitle of host publication9th Annual European Symposium Århus, Denmark, August 28–31, 2001 Proceedings
EditorsFriedhelm Meyer auf der Heide
ISBN (Electronic)978-3-540-44676-7
ISBN (Print)978-3-540-42493-2
Publication statusPublished - 2001

Publication series

NameLecture Notes in Computer Science
ISSN (Print)0302-9743
ISSN (Electronic)1611-3349


  • METIS-202692


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