Complete Propagation Rules for Lexicographic Order Constraints over Arbitrary Domains

  • Thom Frühwirth
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 3978)


We give an efficiently executable specification of the global constraint of lexicographic order in the Constraint Handling Rules (CHR) language. In contrast to previous approaches, the implementation is short and concise without giving up on the best known worst case time complexity. It is incremental and concurrent by nature of CHR. It is provably correct and confluent. It is independent of the underlying constraint system, and therefore not restricted to finite domains. We have found a direct recursive decomposition of the problem. We also show completeness of constraint propagation, i.e. that all possible logical consequences of the constraint are generated by the implementation. Finally, we report about some practical implementation experiments.


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Copyright information

© Springer-Verlag Berlin Heidelberg 2006

Authors and Affiliations

  • Thom Frühwirth
    • 1
  1. 1.Faculty of Computer ScienceUniversity of UlmGermany

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