Formal Semantics for Time in Databases

The concept of an historical database is introduced as a tool formodelling the dynamic nature of some part of the real world. Just as first-orderlogic has been shown to be a useful formalism for expressing andunderstanding the underlying semantics of the relational database model,intensional logic is presented as an analogous formalism for expressing andunderstanding the temporal semantics involved in an historical database.The various components of the relational model, as extended to includehistorical relations, are discussed in terms of the model theory for the logicILs, a variation of the logic IL formulated by Richard Montague. Themodal concepts of intensional and extensional data constraints andqueries are introduced and contrasted. Finally, the potential application ofthese ideas to the problem of Natural Language Database Querying is discussed