Entity-generating Schema Transformations for Entity-Relationship Models

The paper is a contribution to the problem of semantics-preserving schema restructuring. First, the notion of schema transformation is precisely analysed, its properties of reversibility are stated and an adequate notation is proposed. Then, the paper develops a general family of entity-generating transformations, i.e. operations that add/remove entity types in a schema. This generic transformation is proved to be able to generate not only a large number of popular E-R schema transformations, but also some powerful new ones.