抄録
There are several abstraction levels for qualitative modeling and reasoning. After two years efforts to use the current level of qualitative reasoning for the process diagnosis of existing chemical processing plant, we found that the abstraction level of reasoning and granularity of the model is too precise for our porpose. It is not only possible for getting the qualitative modeling of existing process with consistent contexts but unnecessary to generate the dynamic causal path for such detailed variables.
We developed a more abstract level of a qualitative reasoning. The reasoning is done directly on the toplogy of 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 the most of existing process plant. In the reasoning, contexts such as set fixed over time or 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 intermediate form of diagnostic knowledge expressed as trees where the given root event is developed for its cause dicection and effect direction.
