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.
supported by NSERC and the Information Technology Research Centre of Ontario
supported by Deutsche Forschungsgemeinschaft under grant Wa 549/1;
supported by the Alexander von Humboldt-Stiftung;
supported by Deutsche Forschungsgemeinschaft under grant ME 872/1-4;
supported by NSERC and the Information Technology Research Centre of Ontario
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© 1992 Springer-Verlag Berlin Heidelberg
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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. https://doi.org/10.1007/3-540-55706-7_3
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DOI: https://doi.org/10.1007/3-540-55706-7_3
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