Sometimes less ambiguous, are extremely complex.

Letters to the editor on the lack of a central index to the field's published works and the fact that many original works are not published in journals; praise for Letovsky article -- stimulating and amusing. felt subsequent letters to editors were full of bombastic indignation; criticism of Kasday letter about it and Bob Engelmore's weak support of the article; dualism in regards to Letovsky letter; and a reply to criticism by Letovsky, acknowledging diaristic form.

VT (vertical transportation) is an expert system for handling the design of elevator systems that is currently in use at Westinghouse Elevator Company. Although VT tries to postpone each decision in creating a design until all information that constrains the decision is known, for many decisions this postponement is not possible. In these cases, VT uses the strategy of constructing a plausible approximation and successively refining it. VT uses domain-specific knowledge to guide its backtracking search for successful refinements. The VT architecture provides the basis for a knowledge representation that is used by SALT, an automated knowledge-acquisition tool. SALT was used to build VT and provides an analysis of VT's knowledge base to assess its potential for convergence on a solution.

Kvetoslav "Slava" Prazdny, who died September 19, 1987 in a hang-gliding accident in the California mountains, was recognized internationally as an expert in many aspects of human and machine perception. He had published over 60 articles reporting research in human perception, stereo vision, image processing, robotics, perceptual reasoning and learning, adaptive neural networks, and psychophysics. A redwood tree in Big Basin State Park is dedicated in his memory.

He then the Sempervirens Fund Anyone wishing Kvetoslav "Slava" Prazdny died in a completed a Ph.D. in Computer Science to make a tribute can do so in Slava's hang-gliding accident, Saturday, at the University of Essex. His name to The Sempervirens Fund, P 0 September 19th, 1987, in the California work reflected the marriage of these Drawer BE, Los Altos, California 94023 mountains. He is survived by his disciplines, as he strove to develop wife, Dagmar Dolan, and his 15 year formal computational models of old daughter Bronja Prazdny. During He was a member of American his prolific career, he had published Association for Advancement of Science, over 60 journal articles reporting American Association for Artificial research in human perception, Intelligence, The Cognitive Science stereo vision, image processing, Society, The Psychonomic Soci-robotics, perceptual reasoning and ety, International Society for Ecological learning, adaptive neural networks, Psychology, Society for Information and psychophysics. Display, SPIE, and a Fellow of the Slava derived his greatest pleasure New York Academy of Sciences.

Sargur N. Srihari is a professor and acting chairman of the Department of Computer Science, State University of New York (SUNY) at Buffalo. The author of "Recognizing Address Blocks on Mail Pieces," Srihari is an associate editor of the journal Pattern Recognition and is chairman of the technical committee on text-processing applications of the International Mike Baird, who coauthored the tribute to Kvetoslav Prazdny, is manager of Association for Pattern Recognition. Srihari is also currently directing two Intelligence Center 1185 Coleman Avenue, Santa Clara, California 95052. Jeffrey Stone is a consultant who watches the computer industry and Jonathan J. Hull is a research assistant Digital Equipment Corporation that reports new developments and trends. The opinions expressed "Recognizing Address Blocks on Mail address is Knowledge Systems Corporation, in his article are his own. Jeffrey Stout is on the research staff of computer vision, and artificial intelligence. An Expert Elevator report on AI and education, is an Buffalo, where he is also currently Designer that Uses Knowledge-Based associate professor in the Department working on his Ph.D. His research Backtracking." of Mathematics and Computer Science interests include image processing, at Millersville University, computer graphics, and computer segmentation Jay M. Tenenbaum, who coauthored Millersville, Pennsylvania 1755 1. Palumbo is a the tribute to Kvetoslav Prazdny, is a coauthor of "Recognizing Address Schlumberger Fellow at the Schlumberger John McDermott is a principal scientist Blocks on Mail Pieces."

VT (vertical transportation) is an expert system for handling the design of elevator systems that is currently in use at Westinghouse Elevator Company. Although VT tries to postpone each decision in creating a design until all information that constrains the decision is known, for many decisions this postponement is not possible. In these cases, VT uses the strategy of constructing a plausible approximation and successively refining it. VT uses domain-specific knowledge to guide its backtracking search for successful refinements. The VT architecture provides the basis for a knowledge representation that is used by SALT, an automated knowledge-acquisition tool. SALT was used to build VT and provides an analysis of VT's knowledge base to assess its potential for convergence on a solution.

We offer a simple mechanism, that of metalingual definition (D. G. Hays, The Meaning of a Term is a Function of the Theory in Which It Occurs, SIGLASH Newsletter, 1973, 6, 4:S-11).

The first step in the development of an expert system is the extraction and characterization of the knowledge and skills of an expert. This step is widely regarded as the major bottleneck in the system development process. To assist knowledge engineers and others who might be interested in the development of an expert system, I offer (1) a working classification of methods for extracting an expert's knowledge, (2) some ideas about the types of data that the methods yield, and (3) a set of criteria by which the methods can be compared relative to the needs of the system developer. The discussion highlights certain issues, including the contrast between the empirical approach taken by experimental psychologists and the formalism-oriented approach that is generally taken by cognitive scientists.