expert system, a computer system or program that uses artificial intelligence techniques to solve problems that ordinarily require a knowledgeable human. The method used to construct such systems, knowledge engineering, extracts a set of rules and data from an expert or experts through extensive questioning. This material is then organized in a format suitable for representation in a computer and a set of tools for inquiry, manipulation, and response is applied. While such systems do not often replace the human experts, they can serve as useful adjuncts or assistants. Among some of the successful expert systems developed are INTERNIST, a medical diagnosis tool that contains nearly 100,000 relationships between symptoms and diseases, and PROSPECTOR, an aid to geologists in interpreting mineral data.

Computer-based system designed to respond like a human expert in a given field. Expert systems are built on knowledge gathered from human experts, analogous to a database but containing rules that may be applied to solving a specific problem. An interface allows the user to specify symptoms and to clarify a problem by responding to questions posed by the system. Software tools exist to help designers build a special-purpose expert system with minimal effort. An outgrowth of work in artificial intelligence, expert systems show promise for an ever-widening range of applications. There are now widely used expert systems in the fields of medicine, personnel screening, and education.

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