Saving constraint checks in maintaining coarse-grained generalized arc consistency
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Constraint check plays a central role in establishing generalized arc consistency which is widely used to solve constraint satisfaction problems. In this paper, we propose a new generalized arc consistency algorithm, called GTR, which ensures that the tuples that have been checked to be allowed by a constraint will never be checked again. For each constraint, GTR maintains a dynamic list of the tuples that were checked to be allowed by this constraint and check their validities to identify some values with supports. It is equipped with a mechanism avoiding redundant validity checks. The basic GAC3 algorithm is employed to find a support for the rest values and to add new tuples to the dynamic list. The experiments show that maintaining GTR during search saves a number of constraint checks. It also brings some improvements over cpu time while solving some CSPs with tight constraints.
KeywordsConstraint satisfaction Local consistency Backtracking
This work was supported by the Fundamental Research Funds for the Central Universities (NO. 2412016KJ034), the Education Department of Jilin Province (Project NO. JJKH20170911KJ) and Key Laboratory of Symbolic Computation and Knowledge Engineering of Ministry of Education, Jilin University (NO.93K172017K06).
Compliance with ethical standards
Conflict of interests
The authors declare that they have no conflicts of interest.
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