Global Constraints in Distributed CSP: Concurrent GAC and Explanations in ABT
نویسندگان
چکیده
The expressiveness of Distributed CSP has been recently enhanced to include global constraints. Careful reformulation of contractible global constraints has been shown to improve efficiency. In this paper, we first show that explained global constraints further improves the efficiency in distributed problems, sometimes by over two orders of magnitude. We then propose maintaining GAC concurrently for any global constraint, without reformulation. We show empirically that concurrent GAC significantly reduces both message passing and computation time, achieving an order of magnitude improvement on some distributed meeting scheduling problems.
منابع مشابه
GAC on Conjunctions of Constraints
Applying GAC on conjunctions of constraints can lead to more powerful pruning [1]. We show that there exists a simple heuristic for deciding which constraints might be useful to conjoin. The result is a useful automatic way of improving a CSP model for GAC solving.
متن کاملDomain k-Wise Consistency Made as Simple as Generalized Arc Consistency
In Constraint Programming (CP), Generalized Arc Consistency (GAC) is the central property used for making inferences when solving Constraint Satisfaction Problems (CSPs). Developing simple and practical filtering algorithms based on consistencies stronger than GAC is a challenge for the CP community. In this paper, we propose to combine k-Wise Consistency (kWC) with GAC, where kWC states that e...
متن کاملMin-Domain Ordering for Asynchronous Backtracking
Ordering heuristics are a powerful tool in CSP search algorithms. Among the most successful ordering heuristics are heuristics which enforce a fail first strategy by using the min-domain property [HE80, BR96, SG98, Dec 03]. Ordering heuristics have been introduced recently to Asynchronous backtracking (ABT), for distributed constraints satisfaction (DisCSP) [ZM05]. However, the pioneering study...
متن کاملMessage delay and Asynchronous DisCSP search
Distributed constraint satisfaction problems (DisCSPs) are composed of agents, each holding its own variables, that are connected by constraints to variables of other agents. Due to the distributed nature of the problem, message delay can have unexpected effects on the behavior of distributed search algorithms on DisCSPs. This has been shown in experimental studies of asynchronous backtracking ...
متن کاملGlobal constraints in distributed constraint satisfaction
Global constraints have been crucial for the success of centralized constraint programming. Here, we propose the inclusion of global constraints in distributed constraint satisfaction. We show how this inclusion can be done, considering different decompositions for global contraints. We provide experimental evidence of their benefits on several benchmarks solved with the ABT algorithm.
متن کامل