Domain Reduction for Valued Constraints by Generalising Methods from CSP

  • Martin C. CooperEmail author
  • Wafa Jguirim
  • David A. Cohen
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 11008)


For classical CSPs, the absence of broken triangles on a pair of values allows the merging of these values without changing the satisfiability of the instance, giving experimentally verified reduction in search time. We generalise the notion of broken triangles to VCSPs to obtain a tractable value-merging rule which preserves the cost of a solution.

We then strengthen this value merging rule by using soft arc consistency to remove soft broken triangles and we show that the combined rule generalises known notions of domain value substitutability and interchangeability. Unfortunately the combined rules are no longer tractable to apply, but can still have applications as heuristics for reducing the search space.

Finally we consider the generalisation of another value-elimination rule for CSPs to binary VCSPs. This new rule properly generalises neighbourhood substitutability and so we expect it will also have practical applications.


Valued Constraint Satisfaction Problem Value merging Value elimination Tractability 



We would like to thank Wady Naanaa for useful discussion concerning the generalisation to the general-arity case.


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Copyright information

© Springer Nature Switzerland AG 2018

Authors and Affiliations

  • Martin C. Cooper
    • 1
    Email author
  • Wafa Jguirim
    • 1
    • 2
  • David A. Cohen
    • 3
  1. 1.IRIT, University of Toulouse IIIToulouseFrance
  2. 2.National School of Computer ScienceUniversity of ManoubaManoubaTunisia
  3. 3.Department of Computer ScienceRoyal Holloway, University of LondonEghamUK

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