Model Revision : Techniques and tools for analyzing simulation resultsand revising qualitative modelsDaniel

One of the factors hindering the wide{spread application of qualitative simulation techniques is the diiculty encountered when developing a qualitative model. Analyzing the resulting behavioral description and revising the model in response to this analysis requires a signiicant amount of expertise and is often left up to the modeler. As a result, developing a qualitative model is diicult for users who are not familiar with the eld. Furthermore, this process is often not addressed within the literature making it diicult for such a user to obtain the necessary expertise except through trial and error. This paper addresses the process of model revision and presents a set of tools and methods to assist in the performance of this task. It also demonstrates how qualitative simulation can be used to obtain a more detailed understanding of the dynamical properties of the modeled system. The tools presented help the modeler extract information from a complex behavioral description by providing alternative views of the description, allowing the modeler to perform a focused search of the potential state space and providing explanation facilities for the branches occuring within the description. These tools and the methods are discussed with respect to the development of a semi{quantitative model of a controller for a tank.