SQSIM: a simulator for imprecise ODE models

This article describes a method for representing and simulating ordinary di fferential equation (ODE) systems which are imprecise - that is, where the ODE model contains both parametric and functional uncertainty. Such models, while useful in engineering tasks such as design and hazard analysis, are not used in practice because they require either special structures which l imit the describable uncertainty or produce predictions which are extremely weak. This article describes SQSIM (for SemiQuantitative SIMulator), a sys tem which provides a general language for representing and reasoning about many common forms of engineering uncertainty. By defining the model both qu alitatively and quantitatively and by using a simulation method that combin es inferences across the qualitative-to-quantitative spectrum, SQSIM produc es predictions that maintain a precision consistent with the model imprecis ion. (C) 1998 Elsevier Science Ltd. All rights reserved.