DESIGN SUPPORT TO DETERMINE THE RANGE OF DESIGN PARAMETERS BY QUALITATIVE REASONING

We present a new application of qualitative reasoning to design: sugge sting valid ranges for design parameters after the structure has been determined. This design step is implemented by using an envisioning me chanism that uses qualitative reasoning to determine all possible beha viors of a system. Our method finds all possible behaviors by envision ing with design parameters whose values are initially indeterminate an d with whatever specifications the designer has. If several behaviors are found, the designer selects the ones he prefers. The design-suppor t system Desq (Design support system based on qualitative reasoning) i s based on an earlier qualitative reasoning system Qupras (Qualitative physical reasoning system) with three improvements: envisioning, prop agating new constraints on constant parameters, and solving constraint in parallel. Like Qupras, the Desq system can deal with quantities qu alitatively and quantitatively. Therefore, if the parameters can be ex pressed quantitatively, we may be able to determine the quantitative r anges, which are often more useful than qualitative values.