Improving the Performance of maxRPC

Max Restricted Path Consistency (maxRPC) is a local consistency for binary constraints that can achieve considerably stronger pruning than arc consistency. However, existing maxRPC algorithms suffer from overheads and redundancies as they can repeatedly perform many constraint checks without triggering any value deletions. In this paper we propose techniques that can boost the performance of maxRPC algorithms. These include the combined use of two data structures to avoid many redundant constraint checks, and heuristics for the efficient ordering and execution of certain operations. Based on these, we propose two closely related maxRPC algorithms. The first one has optimal O(end3 ) time complexity, displays good performance when used stand-alone, but is expensive to apply during search. The second one has O(en2 d4 ) time complexity, but a restricted version with O(end4 ) complexity can be very efficient when used during search. Both algorithms have O(ed) space complexity when used stan...

• Type: Journal
• Year: 2010
• Where: CORR
• Authors: Thanasis Balafoutis, Anastasia Paparrizou, Kostas Stergiou, Toby Walsh
• Keywords: Algorithms, Arc Consistency, Constraint Checks, CORR 2010, Education