Information Modeling and Relational Databases, 2nd Edition

14.10. Summary

Conceptual schemas are equivalent iff they model the same UoD. Various schema transformations may be performed to reshape a conceptual schema into one that is either equivalent, or an acceptable alternative.

Predicate specialization fragments a predicate into two or more special cases, typically by absorbing an enumerated object type into it. For example, the association Person is of Gender {‘M’.‘F’} may be specialized into Person is male and Person is female by absorbing Gender.

The inverse transformation, predicate generalization, typically involves extracting an enumerated object type from a predicate. Predicate specialization/generalization (PSG) may also be performed by considering the n cases of a role with a frequency constraint ...