Propositional Satisfiability in Answer-Set Programming

We show that propositional logic and its extensions can support answer-set programming in the same way stable logic programming and disjunctive logic programming do. To this end, we introduce a logic based on the logic of propositional schemata and on a version of the Closed World Assumption. We call it the extended logic of propositional schemata with CWA (PS+, in symbols). An important feature of the logic PS+ is that it supports explicit modeling of constraints on cardinalities of sets. In the paper, we characterize the class of problems that can be solved by finite PS+ theories. We implement a programming system based on the logic PS+ and design and implement a solver for processing theories in PS+. We present encouraging performance results for our approach -- we show it to be competitive with smodels, a state-of-the-art answer-set programming system based on stable logic programming.

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