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Restrictions of access to memory cells.
EREW (exclusive read, exclusive write)
Only one access to individual memory cell at a time.
CREW (concurrent read, exclusive write).
Multiple concurrent reads to a memory cell, but writes are exclusive.
CRCW (concurrent read, concurrent write).
Multiple concurrent writes allowed, random value (maximum value, sum, ...) is written.
Different variants may yield different complexities of parallel algorithms.
Last modification: November 15, 1996