Expert systems (AS Level) flashcards

Topic 7: Expert systems

What is an expert system?

A computer system that stores the knowledge of human experts in one field and uses rules to reason with it, producing possible solutions and explaining how it reached them.

Name the components of an expert system

User interface, inference engine, knowledge base (a database of facts and a rules base), explanation system, and knowledge base editor.

Inference engine vs explanation system

The inference engine does the reasoning: it matches facts to rules, fires rules and decides the next question. The explanation system reports how a conclusion was reached and why a question is asked.

What is the knowledge base editor used for, and by whom?

To add, edit and delete facts and rules so the system stays up to date. It is used by the knowledge engineer or experts, not by the user entering case data.

Forward chaining vs backward chaining

Forward chaining (data driven) starts with known facts and works from IF parts to THEN parts. Backward chaining (goal driven) starts with a goal and works back to test its IF conditions.

Name six scenarios where expert systems are used

Any six of: mineral prospecting, investment analysis, financial planning, insurance planning, car engine fault diagnosis, medical diagnosis, route scheduling for delivery vehicles, plant and animal identification.

Give two advantages and two disadvantages of expert systems

Advantages: consistent with no tiredness; available any time; combines several experts' knowledge; explains its reasoning. Disadvantages: errors in the knowledge base give wrong advice; no common sense; expensive to build; needs updating.