A Default Approach to Semantics of Logic Programs with Constraint Atoms

We define the semantics of logic programs with (abstract) constraint atoms in a way closely tied to default logic. Like default logic, formulas in rules are evaluated using the classical entailment relation, so a constraint atom can be represented by an equivalent propositional formula. Therefore, answer sets are defined in a way closely related to default extensions. The semantics defined this way enjoys two properties generally considered desirable for answer set programming − minimality and derivability. The derivability property is very important because it guarantees free of self-supporting loops in answer sets. We show that when restricted to basic logic programs, this semantics agrees with the conditional-satisfaction based semantics. Furthermore, answer sets by the minimal-model based semantics can be recast in our approach. Consequently, the default approach gives a unifying account of the major existing semantics for logic programs with constraint atoms. This also makes ...

• Type: Conference
• Year: 2009
• Where: LPNMR
• Authors: Yi-Dong Shen, Jia-Huai You
• Keywords: Answer Sets, Artificial Intelligence, Constraint Atoms, Default Logic, LPNMR 2009