In artificial intelligence, an expert system is a computer system emulating the decision-making ability of a human expert.

<artificial intelligence> A computer program that contains a knowledge base and a set of algorithms or rules that infer new facts from knowledge and from incoming data. An expert system is an artificial intelligence application that uses a knowledge base of human expertise to aid in solving problems. The degree of problem solving is based on the quality of the data and rules obtained from the human expert. Expert systems are designed to perform at a human expert level. In practice, they will perform both well below and well above that of an individual expert. The expert system derives its answers by running the knowledge base through an inference engine, a software program that interacts with the user and processes the results from the rules and data in the knowledge base. Expert systems are used in applications such as medical diagnosis, equipment repair, investment analysis, financial, estate and insurance planning, route scheduling for delivery vehicles, contract bidding, counseling for self-service customers, production control and training. [Difference from "knowledge-based system"?] (1996-05-29)

A legal expert system is a domain-specific expert system that uses artificial intelligence to emulate the decision-making abilities of a human expert in the field of law. Legal expert systems employ a rule base or knowledge base and an inference engine to accumulate, reference and produce expert knowledge on specific subjects within the legal domain.

n. opinions stated during trial or deposition (testimony under oath before trial) by a specialist qualified as an expert on a subject relevant to a lawsuit or a criminal case. See also: expert witness

n. a person who is a specialist in a subject, often technical, who may present his/her expert opinion without having been a witness to any occurrence relating to the lawsuit or criminal case. It is an exception to the rule against giving an opinion in trial, provided that the expert is qualified by evidence of his/her expertise, training and special knowledge. If the expertise is challenged, the attorney for the party calling the "expert" must make a showing of the necessary background through questions in court, and the trial judge has discretion to qualify the witness or rule he/she is not an expert, or is an expert on limited subjects. Experts are usually paid handsomely for their services and may be asked by the opposition the amount they are receiving for their work on the case. In most jurisdictions, both sides must exchange the names and addresses of proposed experts to allow pre-trial depositions. See also: expert testimony

n. any testimony of expert scientific, engineering, economic or other specialized nature used to assist the court and the lawyers in a lawsuit or prosecution. See also: forensic forensic medicine

A subject-matter expert (SME) is a person who has accumulated great knowledge in a particular field or topic and this level of knowledge is demonstrated by the person's degree, licensure, and/or through years of professional experience with the subject, i.e.

Joint Expert Speciation System (JESS) is a package of computer software and data developed collaboratively at Murdoch University and elsewhere by researchers interested in the chemical thermodynamics of water solutions with important applications in industry, biochemistry, medicine and the environment. Using information from the chemical literature, stored in databases for numerous chemical properties, JESS achieves coherence between frequently conflicting sources by automatic methods.

Expert Opinion on Biological Therapy is a monthly peer-reviewed medical journal covering research on all aspects of biological therapy, including gene therapy and gene transfer technologies, therapeutic peptides and proteins, vaccines and antibodies, and cell- and tissue-based therapies. The journal is published by Taylor & Francis and the editor-in-chief is Michael Morse (Duke University Hospital).