Browse Books

Reviewer: John M. Artz

Anyone who walks into a technical bookstore today may easily be overwhelmed by the number of volumes available, the variety of subjects addressed, and the depth of titles in any given area. Even if it were economically feasible, temporal constraints would make it impractical to read every volume. Frequently, a choice is made based on cover design and number of illustrations. Sometimes it is made on the strength of the author's name. An astute reader may even browse through the topics or look for the author's objectives. Nonetheless, choosing between the available titles is a challenge. The purpose of this review is to aid in that process. This is a comparative review of five introductory books on expert systems. It is intended to provide a critical overview of each of the five books, including material covered, target audience, and major strengths or weaknesses. These five books represent, as well as possible, a cross section of the types of books available at the introductory level. Tables 1 and 2 below provide a quick overview of the quanti- tative and qualitative points of comparison. Expert systems is a relatively new field and a classic introductory text has yet to emerge. The field has not yet pulled away sufficiently from artificial intelligence and still relies a little too heavily on successfully implemented research projects, such as MYCIN, for validity. Only one chapter out of eight in the Hayes-Roth et al. book presents material which is independent of existing implementations. Harmon and King and Waterman improve that ratio to one-half of the chapters, but both still rely heavily on references to existing applications. The Nagy, Gault, and Nagy book does not rely on this at all, yet neither does it present any conceptual framework. The Hayes-Roth et al. and Waterman books are the first and second volumes in the Teknowledge Series in Knowledge Engineering, and one of the authors of the Harmon and King book is connected to Teknowledge, Inc. While they are producing some of the highest quality books available, the effects of the gene-pool show through in the same basic approach in each volume. This approach, which does vary somewhat from author to author, is to document existing applications and system building tools, while abstracting some general principles as a conceptual framework. This works for now but will weaken as the field progresses. Nagy, Gault, and Nagy offer a different approach entirely, but require access to a microcomputer, some technical background, and perseverance on the part of the reader. Sell again offers a slightly different perspective, but expects an unrealistic level of prior knowledge on the part of the reader, at least for an introductory level book. Following is a short description of each of the five books: Hayes-Roth, Waterman, and Lenat This book, originally published in 1983, was one of the first, if not the first, devoted entirely to expert systems as an endeavor apart from artificial intelligence. It was a bold undertaking because the field of expert systems was just emerging and the conceptual foundations had not yet emerged sufficiently to define a standard and proper development of the topic. The book documents many of the existing expert systems as well as some of the software available for building them. From this, they abstract some general principles and approaches for the development of expert systems. The format is that of a collection of papers, but the editing is adequate so the presentation is fairly consistent. The editors recognize that this effort is ambitious. Yet remarkable progress was made and the roots of many future books may be seen in this volume. It is a little difficult to follow for a first introduction, but a good book to refer back to for a more in-depth look at some of the current thinking in expert systems. It will surely be valuable for some time to come. Although the ideas had not yet crystalized, it provides a wealth of background information and some useful historical perspectives. Harmon and King This is probably the best book, overall, on expert systems available today. It spends three chapters developing some of the conceptual foundations in a clear, readable style with lots of good graphics and examples. It addresses human problem solving, knowledge representation, and drawing inferences with no mention of the existing implementations, and thus serves the future as well as the past. Yet it is not a purely conceptual treatment. The authors explore existing implementations and systems building tools with similar clarity and they pragmatically address the actual development process. The reader begins to get the impression that building expert systems has a lot in common with building information systems. The strengths of this book are its readability and its development of the topic. The authors are, among other things, technical trainers and have a talent for presenting technical material in an understandable fashion. Its major weakness is that, as with many others, it spends a little too much effort on existing implementations. Waterman This is really two books in one and needs to be reviewed as such. The first 22 chapters are a crisp, well-organized introduction to expert systems. The information is well thought out and well presented. This part would serve as an excellent text for an introductory course. The remaining eight chapters (over 150 pages) provide an abundance of supplementary information, such as an annotated catalog of current applications organized by application area and cross-indexed by development tool. The strength of this book lies in its crisp, concise presentation of the issues surrounding the development of expert systems. The major points jump out at the reader, just waiting to be highlighted or underlined. This makes the book particularly useful for a technical manager or a technically oriented business student. The major weakness lies in the divergent focus. Even though it is two books in one, it is not the case that the two books address the same target audience. Nagy, Gault, and Nagy This book represents a different approach to expert systems development. It presents no conceptual framework, and makes no mention of existing applications. Instead, it provides an expert system shell called Micro-PS (a scaled down version of KES) and steps the reader through the development of a prototype expert system. The software is provided with the book and the reader must have access to an IBM-PC or a compatible microcomputer in order to use the software. The reader can build one of the example systems or one of his or her own choosing. With a 20 rule maximum, there is a severe limit on the sophistication of the prototype system. However, it is sufficient to give the reader a feel for a prototype development process and the workings of an expert system shell. The strength of this book is that it helps the reader to overcome some of the conceptual barriers associated with expert systems through hands-on experience. The evolving prototype approach may also be useful for a technical manager attempting to assess the feasibility of expert systems technology for a particular application area. The major weaknesses of the book are that it is a little hard to read and follow, and that it is almost impossible to use without access to a microcomputer. Sell This spartan volume is a highly condensed overview of expert systems development. It is less than 100 pages, with few wasted words and very little in the way of illustration. The style of the book is that of “straight talk” about expert systems from a veteran practitioner to a less seasoned one. All the bases are covered but little time is spent on any one. The first chapter, for example, addresses scientific revolutions, domain-independent versus domain-dependent problem solving, and the paradigm shift in artificial intelligence—all in one paragraph. Whew]] The author states that “It is hoped that the glimpse is sufficient to show that the techniques used are neither too arcane to comprehend nor too intricate to implement.” This objective was met, and not a single word was wasted in the process. The main strength of this book is in its brevity. The reader who has already read many of the introductory books and papers will find it refreshingly concise. Unfortunately, there is a fine line between being terse and being obscure. The reader with less background may become frustrated as large strides are taken in short passages. Conclusion @ The book by Harmon and King is the best, overall, for the person on the street who might walk into a technical bookstore looking for an introductory book on expert systems. Waterman is the best introductory textbook, although Harmon and King would not be a bad choice. Waterman offers the additional advantage that it is written in a style more appropriate for an introductory textbook. The Nagy, Gault, and Nagy book would be a good choice for a hands-on course, but needs either the Harmon and King or the Waterman book for the conceptual framework. Nagy, Gault, and Nagy is also a good choice for a technically oriented individual who wishes to learn by doing and leave the theory for later. Hayes-Roth et al. and Sell are a little less refined and should be attempted after some introductory groundwork has been laid. Both are a bit more obscure and may be a little too much for a first introduction.

Reviewer: John M. Artz

This book is the second book in the Teknowledge Series in Knowledge Engineering, whose mission is to “provide an effective channel for informing and educating people interested in understanding and implementing [expert systems] technology.” Its target audience is “practicing knowledge engineers, student- s, scientists in related disciplines, and technical managers” who wish to assess the potential of expert systems technology. Watermann was one of the editors of the first book in this series [1], and thus the book comes from a good family. The subject of the book, as the title implies, is expert systems. It is oriented toward the reader who is either considering the development of an expert system, or one who wants to know more about the kinds of applications that are well suited to this technology. The book provides a basic introduction to expert systems and addresses a wide range of human, system development, and organizational issues. There are two outstanding aspects of this book which differentiate it from the rest of the crowd of recent releases on expert systems. Both features are superficially mechanical, but reflect important characteristics of the content. First of all, the first 23 chapters average only ten pages apiece. This allows the reader to absorb the material in small, well organized doses without loss of continuity with the overall theme of the book. The author avoids fragmentation by judicious selection for chapter topics; once he has settled on a topic he goes right to the heart of the matter. This is ideal for novice readers and for those who do not have the time or patience to read for more than a few minutes at a time. The second outstanding feature is the internal organization of the chapters. Each chapter presents a topic and then addresses a half dozen salient issues wi- th regard to that topic. It is almost as though the book was written for a pers- on reading with a highlighter pen. The issues are crisp, germane, and the reader never has to search for them. This makes particularly good reading for anyone concerned with the issues surrounding expert systems development, rather than the procedural substance of the process itself. Unfortunately, these two attractive features are buried in a text that attempts to cover too many audiences and thus comes across as being unfocused. The book itself is divided into two parts. The first 200 pages address expert systems development, and is textbook in nature. The second 200 pages provide catalogs, indices, and bibliographies for gathering further information. This is useful reference material but does not add to the completeness of the textbook beginning. The material in the front half also lacks focus. At one extreme it addresses issues, as described above, and at the other extreme it provides very detailed examples from existing systems. It seems unlikely that the same reader would be interested in both conceptual issues and coding examples. There is a lot of good information in this book, which could have been delivered better by a clearer definition of the intended audience. For a survey of the major issues surrounding expert systems development, this book is excellent. Unfortunately, the reader will have to leaf past an abundance of other information which was apparently supplied to round out the intended audience.