Confluence Modulo Equivalence in Constraint Handling Rules

  • Henning ChristiansenEmail author
  • Maja H. Kirkeby
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 8981)


Previous results on confluence for Constraint Handling Rules, CHR, are generalized to take into account user-defined state equivalence relations. This allows a much larger class of programs to enjoy the advantages of confluence, which include various optimization techniques and simplified correctness proofs. A new operational semantics for CHR is introduced that significantly reduces notational overhead and allows to consider confluence for programs with extra-logical and incomplete built-in predicates. Proofs of confluence are demonstrated for programs with redundant data representation, e.g., sets-as-lists, for dynamic programming algorithms with pruning as well as a Union-Find program, which are not covered by previous confluence notions for CHR.


Hide Markov Model Dynamic Programming Algorithm Operational Semantic Critical Pair Derivation Step 
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Copyright information

© Springer International Publishing Switzerland 2015

Authors and Affiliations

  1. 1.Research group PLIS: Programming, Logic and Intelligent Systems Department of Communication, Business and Information TechnologiesRoskilde UniversityRoskildeDenmark

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