We show how the dynamics of database systems can be modeled by making states first-class citizens in an object-oriented deductive database language. With states at the same time acting as objects, methods, or classes, several concepts of dynamic entities can be implemented, allowing an intuitive, declarative modeling of the application domain. Exploiting the natural stratification induced by the state sequence, the approach also provides an implementable operational semantics. The method is applicable to arbitrary object-oriented deductive database languages which provide a sufficiently flexible syntax and semantics. Provided an implementation of the underlying database language, any system specification in the presented framework is directly executable, thus unifying specification, implementation, and metalanguage for proving properties of a system. The concept is applied to F-Logic. Besides the declarative semantics given by the rules of a State-F-Logic program, the use of F-Logic's inheritance semantics for modeling states provides an effective operational semantics exploiting the naturally given state-stratification. State-F-Logic programs can be executed using the Florid implementation.

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