Date of this Version
UNL-CSE-2012-0010 November 19, 2012
Local consistency properties and algorithms for enforcing them are central to the success of Constraint Processing. In this paper, we explore how to exploit the structure of the problem on the performance of the algorithm for enforcing consistency. We propose various strategies for managing the propagation queue of an algorithm for enforcing consistency, and empirically compare their effectiveness for solving CSPs with backtrack search and full lookahead. We focus our investigations on consistency algorithms that operate on the dual graph of a CSP and demonstrate the importance of exploiting a tree decomposition of the dual graph. Further, we note that exploiting structure is particularly striking on unsatisfiable instances. We conjecture that the approach for queue-management strategies benefits virtually all other propagation algorithms.