【摘要】 首先介绍了定性推理、定性控制的产生背景、发展状况及已取得的成就，然后给出了定性控制的三种基本方法，并依次举例做了较为详细的说明．最后对定性控制的优点、缺点及发展趋向做了探讨．更多还原

【Abstract】 In this paper, we first introduce the objective of the qualitative reasoning and qualitative control, their development and their achievement. Second, we give three basic methods in qualitative control and make a detail description for each method. At the end, we discuss the advantage, the disadvantage and the developing trend of qualitative control.更多还原