Implementing Ordered Disjunction Using Answer Set Solvers for Normal Programs

  • G. Brewka
  • Ilkka Niemelä
  • Tommi Syrjänen
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 2424)


Logic programs with ordered disjunction (LPODs) add a new connective to logic programming. This connective allows us to represent alternative, ranked options for problem solutions in the heads of rules: A×B intuitively means: if possible A, but if A is not possible, then at least B. The semantics of logic programs with ordered disjunction is based on a preference relation on answer sets. In this paper we show how LPODs can be implemented using answer set solvers for normal programs. The implementation is based on a generator which produces candidate answer sets and a tester which checks whether a given candidate is maximally preferred and produces a better candidate if it is not. We also discuss the complexity of reasoning tasks based on LPODs.


Logic Program Logic Programming Reasoning Task Preference Criterion Normal Program 
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Copyright information

© Springer-Verlag Berlin Heidelberg 2002

Authors and Affiliations

  • G. Brewka
    • 1
  • Ilkka Niemelä
    • 2
  • Tommi Syrjänen
    • 2
  1. 1.Institut für InformatikUniversität LeipzigLeipzigGermany
  2. 2.Helsinki University of TechnologyHUTFinland

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