Conceptual Modeling of Time-Varying Information
Heidi Gregersen, Christian S. Jensen · 1998
A wide range of database applications manage information that varies over time. Many of the underlying database schemas of these were designed using one of the several versions, with varying syntax and semantics, of the Entity-Relationship (ER) model. In the research community as well as in industry, it is common knowledge that the temporal aspects of the mini-world are pervasive and important, but are also difficult to capture using the ER model. Not surprisingly, several enhancements to the ER model have been proposed in an attempt to more naturally and elegantly support the modeling of temporal aspects of information. Common to the existing temporally extended ER models, few or no specific requirements to the models were given by their designers. With the