DisLog { A System for Reasoning in Disjunctive Deductive Databases

DisLog is a system for reasoning in disjunctive deductive databases. It seeks to combine features of disjunctive logic programming, such as the support for incomplete information, with those of deductive databases, such as all{result inference capabilities. Several basic operators are provided for logical and non{monotonic reasoning: The logical consequence operator derives all logically implied disjunctive clauses from a disjunctive logic program. The non{ monotonic operators are semantically founded on generalizations of the well{ known closed{world{assumption. Reasoning in disjunctive deductive databases is very complex, even for small examples. Many di erent optimization techniques are integrated in DisLog to speed up the application performance. The main techniques rely on a clause tree data structure allowing for an e cient and transparent evaluation. The operators of DisLog can be loaded from a library into a Prolog application. DisLog itself is implemented as a meta{interpreter in Sicstus{Prolog.