Diagnostic expert system inference engine based on the certainty factors model

摘要

An expert system inference engine is described which is based on the utilization of certainty factors, and has a structure similar to Naylor's probabilistic inference engine. After a brief description of the latter, a modified probabilistic criterion is developed which naturally leads to the certainty factors question selection criterion employed in the inference engine. Also, the case in which there is user reporting bias is considered, and a method for dealing with it is presented. The paper discusses the required aspects of the model of certainty factors, and presents the major implementation issues relating to the new inference engine, which is written in pascal.