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Specification and Evaluation of Complex Cardinality Constrains

: Zhou, J.; Baumann, P.
: Fraunhofer-Institut für Graphische Datenverarbeitung -IGD-, Darmstadt

Darmstadt: IGD, 1992
Technischer Bericht
Fraunhofer IGD ()
entity-relationship model; Relationship semantics; April; valence concept

This report describes the valence concept, a general method to specify relationships. This approach is type-based, admits variants and detailed cardinality specifications, and can cope with incomplete intermediate states. Nevertheless, the resulting type definition syntax is easy to understand. The valence concept is introduced in an informal way first, then its set-theoretic formal semantics presented.
Moreover, this report outlines an implementation of the valenve concept. Special emphasis has been placed on minimizing space and time overhead on instance level, but it turns out that data dictionary overhead also keeps within reasonable limits.
The valence concept proposed here is not a complete data model, but a relationship model, which has to be embedded in a data model. As such, it is part of the APRIL system which has been developed at FhG-IGD.