Many techniques for representing knowledge have been proposed, but there have been few reports that compare their application This article presents an experimental comparison of four knowledge representation schemes: a simple production system, a structured production system, a frame system, and a logic system. We built four pilot expert systems to solve the same problem: risk management of a large construction project Observations are made about how the structure of the domain knowledge

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... the implementation of expert systems and their run time efficiency WIT: THINK THAT IT IS NECESSARY to clarify the advantages and disadvantages of knowledge representation techniques from the expert system designer's point of view. Barr and Feigenbaum (1981) point out that "many researchers feel that the representation of knowledge is the key issue at this point in the development of AI." Stefik et al (1982) point out some domain characteristics that affect expert system design: large search spaces, a need for tentative reasoning, time varying and noisy data. These four characteristics are elaborated into eleven case studies, and some guidelines for expert systems construc-