Metalogic as a basis for modelling systems dynamics

A novel method for achieving systems dynamics is proposed. It is suitable for systems that are logical rather than algebraic or topological in structure. The specification of the system is by time-independent laws, and its state is represented as a logical theory that contains the laws and the contingent facts. A state change is modeled as a theory revision using a metalogic proposed by Gardenfors and his colleagues. In this way, the dynamics of systems are separated from their timeless properties, and the latter are used to achieve the former. The resulting behavior is guaranteed to be correct relative to the laws without further verification. Examples from the areas of electronic mail, circuit theory, and file systems are discussed to illustrate the proposal. Attention is also given to the interaction between logic and different choices for knowledge representation. It is shown that the method could be used in interactive prototyping