Towards an Algebraic Semantics for Database Specification

In the framewerk of a modal-algebraic approach to database semantics, the specification of abstract object types on the basis of abstract data types is studied. As a semantic framewerk for determining admissible states and state sequences, a standard universe of "possible objects'' and their interrelationships has to be associated with a schema specification. This paper gives a construction of such a _standard universe from a given key system including certain constraints. There is also an abstract algebraic characterization of the universe Cup to isomorphism) in te~ms of final algebras. Within this framework, a general definition of admissible states and state sequences as the semantics of a schema specification is discussed briefly.