A Generic Entity-Relationship Model

The objective of the paper is to put forward a general framework allowing the specification, comparison and conversion of most information and data models currently proposed for Information System design, be they at the conceptual or at the DBMS levels. That framework is based on an extended relational model that includes the concepts of entity domain and of complex domain. The analysis of the constructs available in current information models, and particularly E-R models, demonstrates the ability of the extended relational model to express these constructs without loss of semantics. The Generic Entity-relationship (GER) model is a large subset of the extended relational model that can uniquely represent the concepts of most current information models, while being more regular, less complex and more powerful than their union. By further augmenting the GER with two simple logical implementation constructs we extend it to the expression of DBMS-dependent models.