A transformation system for deductive database modules with perfect model semantics

We present a transformation system for deductive database (DDB) modules. We show that it preserves several data-dependency properties of a DDB and is correct for the "perfect model" semantics of DDBs. Perfect models are not directly amenable to logical reasoning since logically equivalent DDBs may have different perfect models. We develop an approach which involves using a condition on data dependencies in DDBs (stratification compatibility) to pass from a logical equivalence to equivalence under perfect model semantics. This is readily applicable to the transformation system. © 1993.