Well-Founded Semantics for Logic Programs with Aggregates: Implementation and Experimentation

Aggregate constructs are one of the major linguistic extensions to logic programming. In this paper, we focus on logic programming with monotone and antimonotone aggregate literals with the well-founded semantics defined in [1], which allows for aggregates occurring in recursive definitions. We formally show that computing this semantics is tractable and present a prototype system obtained by modifying DLV. To our knowledge, this is the only system supporting well-founded semantics for logic programs with recursive aggregates. While aggregates yield an obvious representational improvement, we also present experiments involving our prototype system and XSB, showing that aggregates are also beneficial from a computational point of view.