Logic Programs with Ordered Disjunction |
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Authors: | Gerhard Brewka,Ilkka Niemelä , Tommi Syrjä nen |
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Affiliation: | Universität Leipzig, Institut für Informatik, Augustusplatz, Leipzig, Germany; Department of Computer Science and Engineering, Helsinki University of Technology, Finland |
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Abstract: | Logic programs with ordered disjunction (LPODs) contain a new connective which allows representing alternative, ranked options for problem solutions in the heads of rules: A × B intuitively means that 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. 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 and possible applications. |
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Keywords: | logic programs answer set semantics priorities qualitative preferences |
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