Inverse Consistencies for Non-Binary Constraints
نویسندگان
چکیده
We present a detailed study of two inverse consistencies for non-binary constraints: relational path inverse consistency (rel PIC) and pairwise inverse consistency (PWIC). These are stronger than generalized arc consistency (GAC), even though they also only prune domain values. We propose algorithms to achieve rel PIC and PWIC, that have a time complexity better than the previous generic algorithm for inverse consistencies. One of our algorithms for PWIC has a complexity comparable to that for GAC despite doing more pruning. Our experiments demonstrate that inverse consistencies can be more efficient than GAC on a range of non-binary problems.
منابع مشابه
Relational Consistencies
We perform an extensive comparison of relational consistencies along four dimensions: on binary constraints, on non-binary constraints, on encodings of non-binary constraints, and on decomposable non-binary constraints. Our results contain some surprises. For example, on binary constraints, relational path-consistency does not reduce to path-consistency. On non-binary constraints, relational ar...
متن کاملStrong Domain Filtering Consistencies for Non-Binary Constraint Satisfaction Problems
Domain filtering local consistencies, such as inverse consistencies, that only delete values and do not add new constraints are particularly useful in Constraint Programming. Although many such consistencies for binary constraints have been proposed and evaluated, the situation with non-binary constraints is quite different. Only very recently have domain filtering consistencies stronger than G...
متن کاملDomain filtering consistencies for non-binary constraints
In non-binary constraint satisfaction problems, the study of local consistencies that only prune values from domains has so far been largely limited to generalized arc consistency or weaker local consistency properties. This is in contrast with binary constraints where numerous such domain filtering consistencies have been proposed. In this paper we present a detailed theoretical, algorithmic a...
متن کاملNon-Binary Constraints
Since the origins of the constraint satisfaction paradigm, its restriction to binary constraints has concentrated a signiicant part of the work. This is understandable because new ideas/techniques are usually much simpler to present/ elaborate by rst restricting them to the binary case. (See for example the arc consistency algorithms, such as AC-3 or AC-4, which have been presented rst in their...
متن کاملSecond-Order Consistencies
In this paper, we propose a comprehensive study of second-order consistencies (i.e., consistencies identifying inconsistent pairs of values) for constraint satisfaction. We build a full picture of the relationships existing between four basic second-order consistencies, namely path consistency (PC), 3-consistency (3C), dual consistency (DC) and 2-singleton arc consistency (2SAC), as well as the...
متن کامل