NEGATION IN RULE-BASED DATABASE LANGUAGES - A SURVEY

This paper surveys and compares different techniques investigated in order to integrate negation in rule-based query languages. In the context of deductive databases, a rule-based query is a logic program. The survey focuses on the problem of defining the declarative semantics of logic programs with negation. The declarative semantics of logic programs with negation based on fixpoint techniques, based on three-valued logic and based on non-monotonic logics are presented for positive logic programs, (locally) stratifiable logic programs and unstratifiable logic programs. The expressive power of rule-based query languages is examined.