An extended owner-coupled set data model and predicate calculus for database management
ACM Transactions on Database Systems (TODS)
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It is shown that the time dimension may be adequately incorporated in data models by distinguishing between object entity classes and process entity classes. Query language difficulties due to the time dependance of object entity attribute values are overcome by the introduction of the superschema or data supermodel concept. Queries for time decomposition of process instances, i.e. 'how-queries' are possible. However queries requesting the algorithmic decomposition of processes are possible if the data model is further expanded to permit inclusion of the algorithms governing the real world behaviour of the entities modelled in the data base. Three types of retrieval expression formats are presented: GET, GET-HOW, and GET HOW-COULD. Relational and extended owner-coupled set predicate calculus are used in the analysis.