Temporal Deductive Databases: Data Manipulation and Consistency

The notion of deductive database is generalized by extending the rst-order language, used to formulate facts, rules and constraints, to a rst-order language involving time operators. A deductive database based on such an extended language is called temporal. In this paper, we rst introduce two additional time operators, one to reference past tenses, the other to reference future tenses. Then, the notion of temporal deductive database and its consistency is formally deened. Afterwards, the data manipulation facilities of an implemented temporal deductive database management system are presented, and their relationship to the consistency is discussed. This reveals that consistency is hard to achieve within the presented framework. Therefore, the class of present dependent constraints is introduced. The result is that if the constraints are restricted to be present dependent, then any temporal deductive database may easily be made consistent.