Retrieval of scattered information by EREW, CREW and CRCW PRAMs

  • Faith Fich
  • Miroslaw Kowaluk
  • Krzysztof Loryś
  • Miroslaw Kutylowski
  • Prabhakar Ragde
Conference paper

DOI: 10.1007/3-540-55706-7_3

Part of the Lecture Notes in Computer Science book series (LNCS, volume 621)
Cite this paper as:
Fich F., Kowaluk M., Loryś K., Kutylowski M., Ragde P. (1992) Retrieval of scattered information by EREW, CREW and CRCW PRAMs. In: Nurmi O., Ukkonen E. (eds) Algorithm Theory — SWAT '92. SWAT 1992. Lecture Notes in Computer Science, vol 621. Springer, Berlin, Heidelberg

Abstract

The k-compaction problem arises when k out of n cells in an array are non-empty and the contents of these cells must be moved to the first k locations in the array. Parallel algorithms for k-compaction have obvious applications in processor allocation and load balancing; k-compaction is also an important subroutine in many recently developed parallel algorithms. We show that any EREW PRAM that solves the k-compaction problem requires Ω(√log n) time, even if the number of processors is arbitrarily large and k=2. On the CREW PRAM, we show that every n-processor algorithm for k-compaction problem requires Ω(loglog n) time, even if k=2. Finally, we show that O(log k) time can be achieved on the ROBUST PRAM, a very weak CRCW PRAM model.

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Copyright information

© Springer-Verlag 1992

Authors and Affiliations

  • Faith Fich
    • 1
    • 2
  • Miroslaw Kowaluk
    • 3
  • Krzysztof Loryś
    • 3
  • Miroslaw Kutylowski
    • 4
  • Prabhakar Ragde
    • 5
  1. 1.University of TorontoTorontoCanada
  2. 2.MITCambridgeUSA
  3. 3.Universität WürzburgWürzburgGermany
  4. 4.FB Informatik and Heinz-Nixdorf-InstitutUniversität-GH PaderbornPaderbornGermany
  5. 5.University of WaterlooWaterlooCanada
  6. 6.Uniwersytet WarszawskiWarszawaPoland
  7. 7.Uniwersytet WroclawskiWrocławPoland

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