A logical framework for temporal deductive databases

Abstract

Temporal deductive databases are deductive databases with an ability to represent both valid time and transaction time. The work is based on the Event Calculus of Kowalski & Sergot. Event Calculus is a treatment of time, based on the notion of events, in first-order classical logic augmented with negation as failure. It formalizes the semantics of valid time in deductive databases and offers capability for the semantic validation of updates and default reasoning. In this paper, the Event Calculus is extended to include the concept of transaction time. The resulting framework is capable of handling both proactive and retroactive updates symmetrically. Error correction is achieved without deletions by means of negation as failure. The semantics of transaction time is formalised and the axioms of the Event Calculus are modified to cater for temporal databases. Given a description of events, axioms are presented for deducing relationships and the time periods for which they hold with respect to any past/present state of the database .