The reuse and modification of rulebases by predicate substitution
EDBT '90 Proceedings of the 2nd international conference on extending database technology: Advances in Database Technology
Hypothetical reasoning in deductive databases
Hypothetical reasoning in deductive databases
The Semantics of Predicate Logic as a Programming Language
Journal of the ACM (JACM)
Journal of the ACM (JACM)
Contributions to the Theory of Logic Programming
Journal of the ACM (JACM)
Introduction To Automata Theory, Languages, And Computation
Introduction To Automata Theory, Languages, And Computation
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This paper develops a method for reusing and modifying deductive databases. Such methods are needed when new rulebased applications differ only slightly from existing ones or when an application is to be incrementally updated. In order to facilitate reuse, we extend deductive databases by the concept of predicate substitution. In this way, during query evaluation, not only variables, but also predicates can be substituted. This paper continues our earlier work on predicate substitution in two directions: (i We extend the concept to a wider class of rulebase modifications, and (ii) we estblish tight bounds on the data complexity of Datalog augmented with substitution, showing it to be EXPTIME-complete. Predicate substitution thus increases the power of Datalog to express database queries. The paper presents a proof theory and model theory for the language, including a fixpoint semantics.