K.U.Leuven - Departement toegepaste economische wetenschappen
DTEW Research Report 9640 pages:1-37
In Object Orientation, the Generalisation/Specialisation hierarchy and the Whole/Part relationship are prevalent classification schemes for object types. This paper presents a new classification scheme for object types, called 'existence dependency'. Existence dependency captures some of the interesting semantics that are usually associated with the concept of aggregation (Part of relation). In fact, the semantics of existence dependency are hidden in the semantics of the Entity Relationship model, but have never been explicitly named. We will demonstrate how the explicit classification of object types according to the existence dependency relation allows for formal and automatic consistency between static and dynamic aspects of object types that goes far beyond mere syntactical consistency.