Database Updates in Logic Programming

Abstract

The need for control in logic programe is now being recognized This is particularly evident when one focuses on allowing updates in logic programs In this paper we propose a language DatalogA which is an extension of Datalog with updates to base relations We define some procedural constructs to allow update programs to be written m an easy manner The (W, ρ) scheme of Dynamic Logic fits nicely into the semantics of DatalogA programs in which W is taken to be the set of all possible states of the program and ρ is the accessibility relation between states We give declarative semantics and equivalent constructed model semantics for DatalogA programs. We show that m the absence of updates our semantics reduce to the classical semantics of Datalog Finally, we show some examples of non-stratified programs expressed in DatalogA.