Cooperation for Distributed Diagnostic Expert Systems

Work made on cooperation to date has been divided into two different approaches, direct communication and assisted coordination in (M.R.Genesereth and S.P.Ketchpcl ,94). The former includes the contract-net approach (R.G.Smith ,80) and specification sharing(SS), which are proper in small scale cooperation. The latter includes a facilitator and a mediator(M.R.Genesereth ,92), which are better in large scale cooperation. Due to the facts that we are considering only cooperation between two diagnostic expert systems and that it is easy to use our modeling of expert systems, we adopt an SS-based approach to interoperate expert systems. The shared specification comes from a common task ontology (IPST) and a common domain ontology. Although one expert system (originator) can get the information about capabilities of the other expert system (recipient) through the shared specification, it is important to identify the information available to improve the originator. A method to find out the the difference arising in the context of the correspondence between inference primitive of an originator and those of a recipient is presented here as follows:

• Make a set of correspondence in which inference primitives are the same between an originator and a recipient.
• By taking a look at the context (pre-inference-primitive, post-inference primitive, input, output and reference knowledge) of the inference primitive in the correspondence, the correspondence value is computed. The more similar the context, the larger the value.
• The correspondence value is propagated to pre- and post- inference primitives.
• After completing propagation over all inference primitives in the correspondence, the difference arising in the context of the correspondence with large values can be used as a reply message to modify the originator's inference engine.