Empirical rule learning and analytic Most learning is based on experience, and this requires a learning methods have predominantly used the first path, representation for the experiential input given to the whereas connectionist systems have relied on the second.

An early expression of this difficulty is the socalled might be stated that Socrates's birthplace was Athens.

Paper presented at the IPN Symposium 7: Formalized Theories of Thinking and Learning and Their Implications for Science Instruction.

Specialization and generalization are accomplished by adding or deleting elements in these lists. The use of symbolic categories of belief (definite, probable, and possible) provides a specifiable means for manipulating the rules. While based on a simple idea, the SEEK program convincingly demonstrates the value of a rich('v structured representation and of reasoning from cases as a way of constructing a model. That is, exjJert knowledge is inseparable from case experience (Schank, 1983), in so far as knov.Jledge explains the cases. The use of a knowledge base to provide an explanatm), model has characterized other recent AIM work as well (cf.

Working in the EMYCIN environment, they were delighted to find that they could more easily distill their criteria for test interpretation by using the production rule formalism.

The work is also of interest because of its relation to psychological studies (Chapter 12) and explanation methodology (Chapter 16).

This chapter briefly outlines the difference between traditional instructional programs and ICAI. It then illustrates how GUIDON makes contributions in areas important to medical CAl: interacting with the student in a mixed-initiative dialogue (including the problems of feedback and realism), teaching problem-solving strategies, and assembling a computerbased curriculum. In evaluating GUIDON's performance, one can see the value in the basic idea of formalizing teaching knowledge in procedures that are separate from the knowledge to be taught. However, the program is inherently limited by the MYCIN knowledge base. The rule set is poorly structured, does not contain pathophysiological knowledge for justifying the diagnostic associations, and does not explicitly state the strategies for gathering information and focusing on hypotheses.

Since the early 1970s, researchers in computer-based medical reasoning have begun to recognize the potential benefits of applying symbolic reasoning techniques in clinical domains (see Chapter 3). One such research group is the Heuristic Programming Project at Stanford University. The first medical reasoning program developed by the project, known as the MYCIN system (Shortliffe, 1976), adopted symbolic processing techniques largely in response to a conviction that computer-based consultation systems, in order to be accepted by physicians, should be able to explain how and why a particular conclusion has been derived. Such systems should also be able to incorporate, organize, manipulate, and update large quantities of medical knowledge. Subsequently, a series of additional medical application programs using MYCIN's techniques has been created.

Turing's test (see evaluation) smart instruments, 345

Chapter 10 Chapter 11 Chapter 12 Using Rules The Evolution of MYCIN's Rule Form The Structure of the MYCIN System William van Melle Details of the Consultation System Edward H. Shortliffe Details of the Revised Therapy Algorithm WiUiam J. Clancey Building a Knowledge Base Knowledge Engineering Completeness and Consistency in a Rule-Based System Motoi Suwa, A. Carlisle Scott, and Edward H. Shortliffe Interactive Transfer of Expertise Randall Davis Reasoning Under Uncertainty Uncertainty and Evidential Support A Model of Inexact Reasoning in Medicine Edward H. Shortliffe and Bruce G. Buchanan Probabilistic Reasoning and Certainty Factors J. Barclay Adams 55 67 78 133 149 159 171 209 233 263