Object-oriented programming: themes and variations

The paper delineates three different approaches to expert-system development: the low road that involves direct symbolic programming, the high road that involves building a system that contains explicit representation of the knowledge of some matter, and a middle-road system such as Mycin that is between these two extremes. The development of expert systems at Digital Equipment Corporation, Xerox, and Schlumberger is discussed. Perhaps the most valuable portion of the paper is the discussion of the criteria for the selection of an appropriate problem for an expert system. Also of value are the guidelines for managing the stages of development in an expert system. This is a well-written, informative paper that should be required reading for anyone contemplating building an expert system.