Towards polymorphic relationships in the entity-relationship model

摘要

Despite the flexibility offered by existing conceptual modelling techniques there remains a number of problems that are not well accommodated. Some of these relate to the relatively restricted (and static) modelling of relationships and a large number of these problems relate to the restricted notion of cardinality constraints. In this paper we revisit the concept of cardinality and show how some of the outstanding conceptual modelling issues can be handled in an intuitive manner if a revised view of cardinalities is adopted.