Comments on Samal and Henderson: Parallel consistent labeling algorithms

Journal Article · Thu Dec 01 04:00:00 EST 1988 · International Journal of Parallel Programming; (USA)

DOI:https://doi.org/10.1007/BF01407817· OSTI ID:6389097

Swain, M J ^[1]

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1. Univ. of Rochester, NY (USA)

Samal and Henderson claim that any parallel algorithm for enforcing arc consistency in the worst case must have {Omega}(na) sequential steps, where n is the number of nodes, and a is the number of labels per node. The authors argue that Samal and Henderon's argument makes assumptions about how processors are used and give a counterexample that enforces arc consistency in a constant number of steps using O(n{sup 2}a{sup 2}2{sup na}) processors. It is possible that the lower bound holds for a polynomial number of processors; if such a lower bound were to be proven it would answer an important open question in theoretical computer science concerning the relation between the complexity classes P and NC. The strongest existing lower bound for the arc consistency problem states that it cannot be solved in polynomial log time unless P = NC.

• OSTI ID: 6389097
• Journal Information: International Journal of Parallel Programming; (USA), Journal Name: International Journal of Parallel Programming; (USA) Vol. 17:6; ISSN IJPPE; ISSN 0885-7458
• Country of Publication: United States
• Language: English

Related Subjects

99 GENERAL AND MISCELLANEOUS
990200* -- Mathematics & Computers
ALGORITHMS
ARRAY PROCESSORS
BOUNDARY CONDITIONS
COMPUTER ARCHITECTURE
COMPUTER CALCULATIONS
COMPUTER CODES
DATA PROCESSING
FUNCTIONS
MATHEMATICAL LOGIC
MATHEMATICS
PARALLEL PROCESSING
POLYNOMIALS
PROCESSING
PROGRAMMING
SET THEORY
TASK SCHEDULING