Qualitative reasoning on flow networks and its applications-Reasoning without qualitative equations

There are several abstraction levels for qualitative modeling and reasoning. After two years of efforts to use the current level of qualitative reasoning for the process diagnosis of an existing chemical processing plant, the authors found that the abstraction level of reasoning and granularity of the model is too precise for their purpose. It is not only impossible to get the qualitative modeling of the existing process with consistent contexts but also unnecessary to generate the dynamic causal path for such detailed variables. The authors developed a more abstract level of qualitative reasoning. The reasoning is done directly on the topology of the process flow obtained from a process flow diagram. Qualitative equations used in so far proposed qualitative reasonings are not needed. This level of qualitative reasoning seems more adequate to figure out the large-scale systems found in most existing process plants. In the reasoning, contexts such as a set fixed over time or a set free are made explicit on flows, which are critical for the reasoning. The inference engine for this flow level reasoning is applied to generate an intermediate form of diagnostic knowledge expressed as trees where the given root event is developed for its cause direction and effect direction. [In Japanese.]