A unified representation for numerical and qualitative simulations

Abstract

Models fall naturally into two main categories, those of discrete systems and those of continuous systems. Our model-based reasoning work deals with continuous systems, augmented to provide for the possibility that one continuous system model transitions to another, as when a threshold event occurs such as a thermostat turning on.One aspect of model-based reasoning is simulation. A model is defined and its behavior(s) inferred through qualitative or numerical simulation. The simulated trajectories then facilitate tasks that one expects model-based reasoning to aid in, such as prediction, monitoring, diagnosis, and design.Here we describe an approach to representing simulation trajectories that results in descriptions of system behavior that contain both qualitative and quantitative information about trajectories closely integrated together. Those descriptions are supported by an internal, representation methodology that also closely integrates qualitative and quantitative information. The internal representation methodology supports quantitative inferences about the trajectories, and an example trace of such inferencing is provided.