Constructing interpretations of deductive databases using reduction and dynamic stratification

The family of dynamic interpretations for unstratified deductive databases is introduced and studied. Such interpretations are defined from a base sem antics using dynamic stratification (which in turn relies upon any natural stratification of the database), and reduction operators (which eliminate r ules and dependencies which spuriously affect the natural stratification). Dynamic interpretations coincide with perfect models in the stratified case , and can also be employed to construct perfect models of disjunctive strat ified databases. We characterise precisely those dynamic interpretations th at are consistent with the well-founded model, and show that a certain clas s of dynamic interpretations coincides with stable models. We also present briefly a class of dynamic interpretations that can be regarded as being an alogous to extensions of the well-founded model such as WFs, GWFS, EWFS and WFS+. (C) 2001 Elsevier Science B.V. All rights reserved.