INFORMATIONRETRIEVALINFORMATIONRETRIEVAL
C. J. van Rijsbergen b .Sc. Ph.D. m .b .c .s .
Computer Laboratory
Cambridge University

BUTTERWORTHSLondon & Boston

THE BUTTERWORTH GROUPENGLAND
Butterworth & Co (Publishers) Ltd
London: 88 Kingsway, WC2B 6AB
AUSTRALIA 'Butterworths Pty Ltd
Sydney: 586 Pacific Highway, NSW 2067
Melbourne: 343 Little Collins Street, 3000
Brisbane: 240 Queen Street, 4000
CANADA
Butterworth & Co (Canada) Ltd
Toronto: 2265 Midland Avenue, Scarborough, Ontario, M1P 4S1
NEW ZEALAND
Butterworths o f New Zealand Ltd
Wellington: 26-28 Waring Taylor Street, 1
SOUTH AFRICA
Butterworth & Co (South Africa) (Pty) Ltd
Durban: 152-154 Gale Street
USA
Butterworth & Co (Publishers) Inc
Reading: 161 Ash Street, Massachusetts, 01867
All rights reserved. No part of this publication may be reproduced or transmitted
in any form or by any means, including photocopying and recording, without thewritten permission of the copyright holder, application for which should beaddressed to the publisher. Such written permission must also be obtained before
any part of this publication is stored in a retrieval system of any nature.
This book is sold subject to the Standard Conditions of Net Books and may not
be re-sold in the UK below the net price given by the Publishers in their current
price list.
First published 1975
© Butterworth & Co (Publishers) Ltd, 1975
ISBN 0 408 70717 8

Library of Congress Cataloging in Publication Data
Van Rijsbergen, C J
Information retrieval.

1943-

Bibliography: p.
1. Information storage and retrieval systems.
I. Title.
75-33024
Z699.V35
029.7
ISBN 0-408-70717-8

Printed in England byThe Whitefriars Press Ltd, London and Tonbridge

PREFACE

The material of this book is aimed at advanced undergraduate
information (or computer) science students, postgraduate libraryscience students, and research workers in the field of IR. Some of thechapters, particularly Chapter 6, make simple use of a little advanced
mathematics. However, the necessary mathematical tools can be easily
mastered from numerous mathematical texts that now exist and in any
case references have been given where the mathematics occur.
I had to face the problem of balancing clarity of exposition withdensity of references. I was tempted to give large numbers of references
but was afraid they would have destroyed the continuity of the text. I
have tried to steer a middle course and not compete with the Annual
Review o f Information Science and Technology.
Normally one is encouraged to cite only works that have been
published in some readily accessible form such as a book or periodical.
Unfortunately much of the interesting work in IR is contained intechnical reports and Ph.D. theses. For example most of the work doneon the SMART system at Cornell is available only in reports. Luckily
many of these are now available through the National Technical
Information Service (U.S.) and University Microfilms (U.K.). I have not
avoided using these sources although if the same material is accessible
more readily in some other form I have given it preference.
I should like to acknowledge my considerable debt to many people
and institutions that have helped me. Let me say first that they areresponsible for many of the ideas in this book but that only I wish to
be held responsible. My greatest debt is to Karen Sparck Jones whotaught me to research information retrieval as an experimental science.
Nick Jardine and Robin Sibson taught me about the theory ofPREFACE

automatic classification. Cyril Cleverdon is responsible for forcing me
to think about evaluation. Mike Keen helped by providing data. Gerry
Salton has influenced my thinking about IR considerably, mainly
through his published work. Ken Moody had the knack of bailing meout when the going was rough and encouraging me to continue
experimenting. Juliet Gundry is responsible for making the text morereadable and clear. Bruce Croft, who read the final draft, made many
useful comments. Ness Barry takes all the credit for preparing themanuscript. Finally, I am grateful to the Office of Scientific andTechnical Information for funding most of the early experimental workon which the book is based; to the King’s College Research Centre forproviding me with an environment in which I could think, and to theDepartment of Information Science at Monash University for providing
me with the facilities for writing.
CJ.v.R

CONTENTS

Chapter One

Introduction

1

Chapter Two

Automatic Text Analysis

12

Chapter Three

Automatic Classification

29

Chapter Four

File Structures

56

Chapter Five

Search Strategies

81

Chapter Six

Evaluation95Chapter Seven

The Future133

Bibliography

140

Index149