Model Revision : Techniques and tools for analyzing simulation results and revising qualitative models

One of the factors hindering the wide-spread application of qualitative simulation techniques is the difficulty encountered when developing a qualitative model . Analyzing the resulting behavioral description and revising the model in response to this analysis requires a significant amount of expertise and is often left up to the modeler. As a result, developing a qualitative model is difficult for users who are not familiar with the field . Furthermore, this process is often not addressed within the literature making it difficult 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 .