複数の制約ソルバーを結合した非線形不等式制約ソルバー

抄録

Qualitative reasoning deals with quantities qualitatively, and it can estimate the value of quantities that change continuously during dynamic behaviour. Many applications of qualitative reasoning, for example to diagnoses and designs, have been tried. However, there is one problem. The use of qualitative values causes ambiguities in reasoning. We use inequalities to solve this problem. In this approach, we can deal with quantities both qualitatively and quantitatively. If a quantity is known only qualitatively, its value is described as an inequality. However, if a quantity is known quantitatively, its value is described as an equality without changing its value to a qualitative one. Therefore, we can reduce ambiguities caused by changing a quantitative value to a qualitative one. To use nonlinear inequalities, we developed a nonlinear inequalities constraint solver, CONSORT (Constraint Solver for Nonlinear Inequalities). CONSORT combines three constraint solvers, which use Interval method, Simplex method and Groebner base method. By transferring results amongst the three constraint solving methods, CONSORT can solve a broader range of inequality problems than is possible using on individual method. Moreover, CONSORT can analyze positive and negative feedbacks by using the interval method constraint solver. CONSORT was used as a constraint solver of Desq (Design Support System using Qualitative Reasoning) which supports to determine the values of design parameters within electronic circuits.