Improving Semi-Quantitative Reasoning by Landmark Approximation

Abstract

Many extensions to existing qualitative simulation packages allow combined use of available numeric and qualitative information. Some provide numeric integration across two qualitative states but none of them highlights numerically or semi-quantitatively the qualitatively predicted time points. Moreover, high accuracy at time points is only achieved by a fine level of granularity across the entire time interval. This paper presents landmark approximation as a new methodology to improve semi-quantitative predictions in qualitative simulation. We also present a transition table and a method to propagate semi-quantitative values that is suitable for landmark approximation. These techniques have been implemented in a simulation engine that is based on qualitative reasoning techniques with a semi-quantitative extension. We demonstrate that a semi-quantitative approximation to landmarks improves the predictive power of the simulation tool even with a reduced number of inter..