Increasing Constraint Propagation by Redundant Modeling: an Experience Report
 B. M. W. Cheng,
 K. M. F. Choi,
 J. H. M. Lee,
 J. C. K. Wu
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This paper describes our experience with a simple modeling and programming approach for increasing the amount of constraint propagation in the constraint solving process. The idea, although similar to redundant constraints, is based on the concept of redundant modeling. We introduce the notions of CSP model and model redundancy, and show how mutually redundant models can be combined and connected using channeling constraints. The combined model contains the mutually redundant models as submodels. Channeling constraints allow the submodels to cooperate during constraint solving by propagating constraints freely amongst the submodels. This extra level of pruning and propagation activities becomes the source of execution speedup. reallife nurse rostering system. We perform two case studies to evaluate the effectiveness and efficiency of our method. The first case study is based on the simple and wellknown nqueens problem, while the second case study applies our method in the design and construction of a reallife nurse rostering system. Experimental results provide empirical evidence in line with our prediction.
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 Title
 Increasing Constraint Propagation by Redundant Modeling: an Experience Report
 Journal

Constraints
Volume 4, Issue 2 , pp 167192
 Cover Date
 19990501
 DOI
 10.1023/A:1009894810205
 Print ISSN
 13837133
 Online ISSN
 15729354
 Publisher
 Kluwer Academic Publishers
 Additional Links
 Topics
 Keywords

 Constraint propagation
 redundant modeling
 Authors
 Author Affiliations

 1. Department of Computer Science and Engineering, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China