Propagation Redundancy in Redundant Modelling

  • Chiu Wo Choi
  • Jimmy Ho Man Lee
  • Peter J. Stuckey
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 2833)


Combining mutually redundant models with channelling constraints increases constraint propagation. However, the extra computation efforts of the additional variables and constraints may outweigh the gain of reduction in search space. In fact, many of the constraints in redundant modelling are not only logically redundant but also propagation redundant and hence cannot further reduce search space. We give general theorems for proving propagation redundancy of one constraint with respect to channelling constraints and constraints in the other model. We define a broad form of channelling constraints that are covered by our approach. We illustrate, using problems from CSPLib (, how detecting and removing propagation redundant constraints can significantly speed up solving behaviour.


Channel Function Integer Variable Propagation Redundancy Redundant Constraint Interval Constraint 
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  1. 1.
    Abdennadher, S., Rigotti, C.: Automatic generation of rule-based solvers for intentionally defined constraints. IJAIT 11(2), 283–302 (2002)Google Scholar
  2. 2.
    Apt, K., Monfroy, E.: Constraint programming viewed as rule-based programming. Theory and Practice of Logic Programming 1(6), 713–750 (2001)zbMATHCrossRefMathSciNetGoogle Scholar
  3. 3.
    Bessiére, C., Régin, J.: Arc consistency for general constraint networks: preliminary results. In: IJCAI 1997 pp. 398–404 (1997)Google Scholar
  4. 4.
    Cheng, B., et al.: Increasing constraint propagation by redundant modelling: an experience report. Constraints 4(2), 167–192 (1999)zbMATHCrossRefGoogle Scholar
  5. 5.
    Choi, C.W., Lee, J.H.M., Stuckey, P. J.: Propagation Redundancy for Permutation Channel. In: IJCAI 2003 (to appear)Google Scholar
  6. 6.
    Hnich, B., Kiziltan, Z., Walsh, T.: Modelling a balanced academic curriculum problem. In: Van Hentenryck, P. (ed.) CP 2002. LNCS, vol. 2470, pp. 121–131. Springer, Heidelberg (2002)Google Scholar
  7. 7.
    Smith, B.M.: Modelling a permutation problem. Research Report 2000.18, School of Computer Studies, University of Leeds (2000)Google Scholar
  8. 8.
    Smith, B.M.: Dual models in constraint programming. Research Report 2001.02, School of Computer Studies, University of Leeds (2001)Google Scholar
  9. 9.
    Walsh, T.: Permutation problems and channelling constraints. In: Nieuwenhuis, R., Voronkov, A. (eds.) LPAR 2001. LNCS (LNAI), vol. 2250, pp. 377–391. Springer, Heidelberg (2001)CrossRefGoogle Scholar
  10. 10.
    Brand, S.: Anote on redundant rules in rule-based constraint programming. In: Recent Advances in Constraints, pp. 109–120 (2003)Google Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2003

Authors and Affiliations

  • Chiu Wo Choi
    • 1
  • Jimmy Ho Man Lee
    • 1
  • Peter J. Stuckey
    • 2
  1. 1.Department of Computer Science and EngineeringThe Chinese University of Hong KongShatin, N.T., Hong Kong SARChina
  2. 2.Deptartment of Computer Science & Software EngineeringUniversity of MelbourneAustralia

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