The influence of lookahead in competitive paging algorithms

Extended abstract
  • Susanne Albers
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 726)


We introduce a new model of lookahead for on-line paging algorithms and study several algorithms using this model. A paging algorithm is on-line with strong lookahead l if it sees the present request and a sequence of future requests that contains l pairwise distinct pages. These pages also differ from the page requested by the present request. We show that strong lookahead has practical as well as theoretical importance and significantly improves the competitive factors of on-line paging algorithms. This is the first model of lookahead having such properties. In addition to lower bounds we present a number of deterministic and randomized on-line paging algorithms with strong lookahead which are optimal or nearly optimal.


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  1. [B66]
    L.A. Belady. A study of replacement algorithms for virtual storage computers. IBM Systems Journal, 5:78–101, 1966.Google Scholar
  2. [BBKTW90]
    S. Ben-David, A. Borodin, R.M. Karp, G. Tardos and A. Wigderson. On the power of randomization in on-line algorithms. In Proc. 22nd Annual ACM Symposium on Theory of Computing, pages 379–386, 1990. To appear in Algorithmica.Google Scholar
  3. [CGS89]
    F.K. Chung, R. Graham and M.E. Saks. A dynamic location problem for graphs. Combinatorica, 9(2):111–131, 1989.Google Scholar
  4. [FKLMSY91]
    A. Fiat, R.M. Karp, M. Luby, L.A. McGeoch, D.D. Sleator and N.E. Young. Competitive paging algorithms. Journal of Algorithms, 12:685–699, 1991.Google Scholar
  5. [G91]
    E. Grove. The harmonic online k-server algorithm is competitive. In Proc. 23nd Annual ACM Symposium on Theory of Computing, pages 260–266, 1991.Google Scholar
  6. [HS92]
    M.M. Halldórsson and M. Szegedy. Lower bounds for on-line graph coloring. In Proc. 3rd Annual ACM-SIAM Symposium on Discrete Algorithms, pages 211–216, 1992.Google Scholar
  7. [I90]
    S. Irani. Coloring inductive graphs on-line. In Proc. 31st Annual IEEE Symposium on Foundations of Computer Science, pages 470–479, 1990.Google Scholar
  8. [KT91]
    M.-Y. Kao and S.R. Tate. Online matching with blocked input. Information Processing Letters, 38:113–116, May 1991.Google Scholar
  9. [KMRS88]
    A.R. Karlin, M.S. Manasse, L. Rudolph and D.D. Sleator. Competitive snoopy caching. Algorithmica, 3(1):79–119, 1988.Google Scholar
  10. [MMS88]
    M.S. Manasse, L.A. McGeoch and D.D. Sleator. Competitive algorithms for on-line problems. In Proc. 20th Annual ACM Symposium on Theory of Computing, pages 322–333, 1988.Google Scholar
  11. [MS91]
    L.A. McGeoch and D.D. Sleator. A strongly competitive randomized paging algorithm. Algorithmica, 6:816–825, 1991.Google Scholar
  12. [R89]
    P. Raghavan. Lecture notes on randomized algorithms. IBM Research Report No. RC 15340 (# 68237), Yorktown Heights, 1989.Google Scholar
  13. [RS89]
    P. Raghavan and M. Snir. Memory versus randomization in on-line algorithms. In Proc. 16th International Colloquium on Automata, Languages and Programming, Springer Lecture Notes in Computer Science, Vol. 372, pages 687–703, 1989.Google Scholar
  14. [ST85]
    D.D. Sleator and R.E. Tarjan. Amortized efficiency of list update and paging rules. Communication of the ACM, 28:202–208, 1985.Google Scholar
  15. [S77]
    J.R. Spirn. Program Behavior: Models and Measurements. Elsevier, New York, 1977.Google Scholar
  16. [Y77]
    A.C.-C. Yao. Probabilistic computations: Towards a unified measure of complexity. In Proc. 17th Annual IEEE Symposium on Foundations of Computer Science, pages 222–227, 1977.Google Scholar
  17. [Y91]
    N. Young. Competitive Paging and Dual-Guided On-Line Weighted Caching and Matching Algorithms. Ph.D. thesis, Princeton University, 1991. Available as Computer Science Department Technical Report CS-TR-348-91.Google Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 1993

Authors and Affiliations

  • Susanne Albers
    • 1
  1. 1.Max-Planck-Institut für InformatikSaarbrückenGermany

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