Exploiting Structure in Constraint Propagation

Authors

Robert J. Woodward, University of Nebraska-LincolnFollow
Shant K. Karakashian, University of Nebraska-LincolnFollow
Berthe Y. Choueiry, University of Nebraska-LincolnFollow
Christian Bessiere, University of Montpellier, FranceFollow
David B. Marx, University of Nebraska-LincolnFollow

Date of this Version

2012

Citation

UNL-CSE-2012-0010 November 19, 2012

Comments

Copyright 2012 University of Nebraska-Lincoln

Abstract

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.