Recent Advances in Constraints
Volume 2627 of the series Lecture Notes in Computer Science pp 1530
CGRASS: A System for Transforming Constraint Satisfaction Problems
 Alan M. FrischAffiliated withAI Group, Dept. Computer Science, University of York
 , Ian MiguelAffiliated withAI Group, Dept. Computer Science, University of York
 , Toby WalshAffiliated withCork Constraint Computation Center, University College Cork
Abstract
Experts at modelling constraint satisfaction problems (CSPs) carefully choose model transformations to reduce greatly the amount of effort that is required to solve a problem by systematic search. It is a considerable challenge to automate such transformations and to identify which transformations are useful. Transformations include adding constraints that are implied by other constraints, adding constraints that eliminate symmetrical solutions, removing redundant constraints and replacing constraints with their logical equivalents. This paper describes the CGRASS (Constraint Generation And Symmetrybreaking) system that can improve a problem model by automatically performing transformations of these kinds. We focus here on transforming individual CSP instances. Experiments on the Golomb ruler problem suggest that producing good problem formulations solely by transforming problem instances is, generally, infeasible. We argue that, in certain cases, it is better to transform the problem class than individual instances and, furthermore, it can sometimes be better to transform formulations of a problem that are more abstract than a CSP.
 Title
 CGRASS: A System for Transforming Constraint Satisfaction Problems
 Book Title
 Recent Advances in Constraints
 Book Subtitle
 Joint ERCIM/CologNet International Workshop on Constraint Solving and Constraint Logic Programming Cork, Ireland, June 19–21, 2002. Selected Papers
 Pages
 pp 1530
 Copyright
 2003
 DOI
 10.1007/3540366075_2
 Print ISBN
 9783540009863
 Online ISBN
 9783540366072
 Series Title
 Lecture Notes in Computer Science
 Series Volume
 2627
 Series Subtitle
 Lecture Notes in Artificial Intelligence
 Series ISSN
 03029743
 Publisher
 Springer Berlin Heidelberg
 Copyright Holder
 SpringerVerlag Berlin Heidelberg
 Additional Links
 Topics
 Industry Sectors
 eBook Packages
 Editors

 Barry O’Sullivan ^{(3)}
 Editor Affiliations

 3. Department of Computer Science, University College Cork
 Authors

 Alan M. Frisch ^{(4)}
 Ian Miguel ^{(4)}
 Toby Walsh ^{(5)}
 Author Affiliations

 4. AI Group, Dept. Computer Science, University of York, York, England
 5. Cork Constraint Computation Center, University College Cork, Ireland
Continue reading...
To view the rest of this content please follow the download PDF link above.