Automating diagnosis at the communication structure level [expert systems]

The communication structure level is a knowledge level that specifies how information flows between types of entities in a domain. At this level, certain kinds of diagnostic reasoning can be performed. It is an intermediate level between the level at which current expert systems are designed (using knowledge acquired from experts) and the level at which deep-reasoning systems perform (based on knowledge of structure, functions, and behavior of the system being diagnosed). A further description of the communication structure level is presented, along with heuristics appropriate for control-hierarchy-type systems. These are described with reference to the specific heuristics developed for AI-SPEAR, an expert system designed to analyze both normal use data and error records for a computer tape drive system. The requirements for a system to generate a diagnostic expert system for control hierarchies are presented