WFS PLUS BRANCH-AND-BOUND EQUALS STABLE MODELS

Though the semantics of nonmonotonic logic programming has been studie d extensively, relatively little work has been done on operational asp ects of these semantics, In this paper, we develop techniques to compu te the well-founded model of a logic program, We describe a prototype implementation and show, based on experimental results, that our techn ique is more efficient than the standard alternating fixpoint computat ion, Subsequently, we develop techniques to compute the set of all sta ble models of a deductive database, These techniques first compute the well-founded semantics and then use an intelligent branch and bound s trategy to compute the stable models, We report on our implementation, as well as on experiments that we have conducted on the efficiency of our approach.