M. C. Escher's "Reptiles" used with permission. (c) 1998
Cordon Art B. V. -
Baarn - Holland. All rights reserved.
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M. C. Escher's "Reptiles" used with permission. (c) 1998
Cordon Art B. V. -
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Knowledge Representation is a book
that provides an overview of the psychology of knowledge representation.
It may also be used for a graduate level course on this topic. This web
site contains some additional information about the book. The book is now
available. Ordering information is available below.
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As I wrote it, I thought of this book as a Michelin Guide to knowledge representation. (I'd call it a Fodor's Guide, but there seems to be a Fodor who has had a few things to say about knowledge representation who has apparently written his own guide). The typical travel guide presents an overview of the place you are going. It defines the boundaries of the region, describes the language and currency and gives sketches of the sights you are likely to see when you get there. The descriptions are never as rich as the sights themselves (or you wouldn't have to go). Invariably, there are suggestions of things to see that you would not have considered as well as sights that your mother's best friend said not to miss, but aren't in the guidebook.
It is my hope that this book serves most of these functions as well. In Chapter 1, I will define what I will take to be a representation, and discuss some foundational issues. Then, Chapters 2-7 will discuss kinds of representations (akin to regions of a country). By kinds of representations, I mean ways that people have thought about representations in the context of psychological, computational or linguistic models. By organizing the book around types of representations, I have tried to bring together things that I think are deeply similar, though they may not traditionally have been thought to be the same. Chapters 8 and 9 focus on the role of specific content in representation, and Chapter 10 draws some general conclusions about the use of representation in cognitive models.
By design, I have written this book to accomodate people just entering the field (like the advanced undergraduates and graduate students who have taken my class on knowledge representation). That means that some approaches have been sketched to give the flavor of what the representational scheme is like. I have tried to provide enough references for other sources of information for people who want deeper treatments of the topics covered here. Like the travel guide, if you see something interesting, go there.
Any travel guide has biases. For example, the authors of the Let's Go series are college undergraduates, and so there is a premium on inexpensive places to eat and drink. Other guides that cater to wealthier clientele include a different list of culinary delights. I also have my biases. My own research has focused on similarity, analogy and categorization. This research focus has had two effects on this book. The most direct influence is that there are a lot of examples that are taken from work on similarity and analogy. A more indirect influence is that the work on similarity and analogy assumes structured relational representations. While I have tried to be evenhanded in my approach to representation in this book, there may be biases which seep through that come from my own research. My deepest bias about knowledge representation is tha t there is no single right way to think about the topic. Rather, different problems require different representational decisions. For this reason, I think it is important to be conversant with many different techniques of representation and to know their strengths and weaknesses. As a result, this book is also a bit like a field artillery guide, in that it is meant to provide information about the weapons available to attack various problems in cognitive science.
In an effort to draw parallels between models that make similar sets of representational assumptions, I have sometimes ignored familiar distinctions that are made in cognitive science. Perhaps the most obvious of these surrounds connectionist models. One might expect a whole chapter on connectionist models in a book on knowledge representation, but a glance at the table of contents will tell you that there isn't one. There is at least a chapter's worth of material on connectionism in the book, but specific connectionist techniques are presented along with other models that make similar representational assumptions. Distributed connectionist models are described along with spatial models of representation, parallel constraint satisfaction networks are presented following a discussion of spreading activation, and techniques for role-argument binding in connectionist models appear in the chapter on structured representations. While this approach is nonstandard, I think it ultimately provides a better indication of how these connectionist tools work.
For the past few years, I have taught a course in knowledge representation. In that course, we read articles about different types of knowledge representation and talk about their strengths and weaknesses. We also tried to focus on how different representational assumptions bias the way we think about different psychological processes. If you are interested in teaching a class using this book, I'd recommend a similar approach. To facilitate class discussion, I have numbered all of the examples throughout the book. The chapters of the book need to be supplemented with papers that provide more of the details than I could include here.
So, who is the target audience for this book? As I said, it was written keeping in mind the graduate students who are seeking an introduction to knowledge representation. However, I think that knowledge representation is a crucial topic for anyone who has an interest in cognitive science, and so I'd recommend it to psychologists in general (except perhaps those whose names already appear on more than three lines of the references section). Also, I think the book may be particularly useful for people in the cognitive science community outside of psychology (such as those working in philosophy of mind or cognitive anthropology) who want to know how psychologists have thought about representation.
Finally, the preface of every academic book has an obligatory paragraph that tells you how to read it. My recommendation is to read it straight through. I have tried to provide pointers from one chapter to another when they discuss related material, but I still think it reads better front to back. If you feel an intense need to skip around, start with Chapter 1. Chapters 5-7 should be read as a group in that order. Chapter 8 should probably be read after chapters 2-7. Chapter 10 makes the most sense if it is read last.
Bon voyage
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Gregory L. Murphy
University of Illinois at Urbana-Champaign
"Markman's book does an admirable job of explaining the ideas of representation. It provides a rare perspective, focusing on what kinds of representations have been used in different areas of research and why. The properties and tradeoffs involved in various types are well illustrated with examples drawn from several areas of cognitive science. Anyone interested in cognitive science will find this book an excellent and and enlightening resource."
Kenneth D. Forbus
Northwestern University
"Markman is honest from the beginning about the goals of the book. He states in the preface that he wants to provide a "Michelin guide to knowledge representation." At this, Markman succeeds admirably. The book is comprehensive and well-written."
Timothy P. McNamara
Contemporary Psychology
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