What is an expert system..?

What is an expert system?. A expert system is a computing system that is capable of expressing and reasoning about some domain of knowledge.

Typical domains are:

• Internal medicine (INTERNIST)
• Geology (PROSPECTOR)
• Chemical analysis (DENDRAL)

The purpose of the expert system is to be able to solve problems or offer advice in that domain.

Expert systems can be distinguished from other kinds of AI program because

They deal with subjects of considerable complexity - subjects that normally requir e a good deal of human expertise. – provide expert-level solutions to complex problems.

They must be fast and reliable;

They must be capable of explaining and justifying solutions – be understandable.

They must be suffciently flexible that new information may be easily accomodated.

Architecture of an expert system:

The knowledge base holds the expertise that the system can deploy

The knowledge-base is constructed by the knowledge engineer inconsultation with the domain expert.

For many expert systems knowledge representation is through the use of rules (could also be frames, semantic nets etc.)

In use, some factsare added to the working memory, which represent observations about the domain.

The inference engine allows permits new inferences to be made from the knowledge in the knowledge base.

These new facts represent conclusions about the state of the domain given the observations.

For a rule-based expert system, the inference engine would bea mechanism for carrying out forward and/or backward chaining.