Existence dependency: The key to semantic integrity betweenstructural and behavioral aspects of object types

摘要

In object-oriented conceptual modeling, thengeneralization/specialization hierarchy and the whole/part relationshipnare prevalent classification schemes for object types. This papernpresents an object-oriented conceptual model where, in the end, objectntypes are classified according to two relationships only. Existencendependency and generalization/specialization. Existence dependencyncaptures some of the interesting semantics that are usually associatednwith the concept of aggregation (also called composition or Part Ofnrelation), but in contrast with the latter concept, the semantics ofnexistence dependency are very precise and its use clear cut. The keynadvantage of classifying object types according to existence dependencynare the simplicity of the concept, its absolute unambiguity, and thenfact that it enables to check conceptual schemes for semantic integritynand consistency. We will first define the notion of existence dependencynand claim that it is always possible to classify objects according tonthis relationship, thus removing the necessity for the Part Of relationnand other kinds of associations between object types. The second claimnof this paper is that existence dependency is the key to semanticnintegrity checking to a level unknown to current object-orientednanalysis methods. In other words: Existence dependency allows us tontrack and solve inconsistencies in an object-oriented conceptual schema