TOWARDS THE SEMANTIC WEB

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1 TOWARDS THE SEMANTIC WEB Ontology-driven Knowledge Management Edited by Dr John Davies British Telecommunications plc ProfessorDieterFensel University of Innsbruck, Austria and Professor Frank van Harmelen Vrije Universiteit, Amsterdam, Netherlands JOHN WILEY & SONS, LTD

3 TOWARDS THE SEMANTIC WEB

5 TOWARDS THE SEMANTIC WEB Ontology-driven Knowledge Management Edited by Dr John Davies British Telecommunications plc ProfessorDieterFensel University of Innsbruck, Austria and Professor Frank van Harmelen Vrije Universiteit, Amsterdam, Netherlands JOHN WILEY & SONS, LTD

6 Copyright 2003 John Wiley &Sons Ltd, The Atrium, Southern Gate, Chichester, West Sussex PO19 8SQ, England Telephone (+44) (for orders and customer service enquiries): Visit our Home Page on or All Rights Reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, scanning or otherwise, except under the terms of the Copyright, Designs and Patents Act 1988 or under the terms of a licence issued by the Copyright Licensing Agency Ltd, 90 Tottenham Court Road, London W1T 4LP, UK, without the permission in writing of the Publisher. Requests to the Publisher should be addressed to the Permissions Department, John Wiley & Sons Ltd, The Atrium, Southern Gate, Chichester, West Sussex PO19 8SQ, England, or ed to permreq@wiley.co.uk, or faxed to (+44) This publication is designed to provide accurate and authoritative information in regard to the subject matter covered. It is sold on the understanding that the Publisher is not engaged in rendering professional services. If professional advice or other expert assistance is required, the services of a competent professional should be sought. Other Wiley Editorial Offices John Wiley & Sons Inc., 111 River Street, Hoboken, NJ 07030, USA Jossey-Bass, 989 Market Street, San Francisco, CA , USA Wiley-VCH Verlag GmbH, Boschstr. 12, D Weinheim, Germany John Wiley & Sons Australia Ltd, 33 Park Road, Milton, Queensland 4064, Australia John Wiley & Sons (Asia) Pte Ltd, 2 Clementi Loop 02 01, Jin Xing Distripark, Singapore John Wiley & Sons Canada Ltd, 22 Worcester Road, Etobicoke, Ontario, Canada M9W 1L1 Library of Congress Cataloging-in-Publication Data Towards the semantic web : ontology-driven knowledge management / edited by John Davies, Dieter Fensel, and Frank van Harmelen. p. cm. Includes bibliographical references and index. ISBN (alk. paper) I. Semantic web. 2. Ontology. 3. Knowledge acquisition (Expert systems) I. Davies, John. II. Fensel, Dieter. III. Van Harmelen, Frank. TK T dc British Library Cataloguing in Publication Data A catalogue record for this book is available from the British Library ISBN Typeset in 10/12pt Times by Deerpark Publishing Services Ltd, Shannon, Ireland. Printed and bound in Great Britain by Biddles Ltd, Guildford and King s Lynn. This book is printed on acid-free paper responsibly manufactured from sustainable forestry in which at least two trees are planted for each one used for paper production.

7 Contents Foreword Biographies List of Contributors Acknowledgments xiii xv xix xxi 1 Introduction 1 John Davies, Dieter Fensel and Frank van Harmelen 1.1 The Semantic Web and Knowledge Management The Role of Ontologies An Architecture for Semantic Web-based Knowledge Management Knowledge Acquisition Knowledge Representation Knowledge Maintenance Knowledge Use Tools for Semantic Web-based Knowledge Management Knowledge Acquisition Knowledge Representation Knowledge Maintenance Knowledge Use 8 2 OIL and DAML + OIL: Ontology Languages for the Semantic Web 11 Dieter Fensel, Frank van Harmelen and Ian Horrocks 2.1 Introduction The Semantic Web Pyramid of Languages XML for Data Exchange RDF for Assertions RDF Schema for Simple Ontologies Design Rationale for OIL Frame-based Systems Description Logics 17

8 vi Contents Web Standards: XML and RDF OIL Language Constructs A Simple Example in OIL Different Syntactic Forms Language Layering Semantics From OIL to DAML+ OIL Integration with RDFS Treatment of Individuals DAML + OIL Data Types Experiences and Future Developments 31 3 A Methodology for Ontology-based Knowledge Management 33 York Sure and Rudi Studer 3.1 Introduction Feasibility Study Kick Off Phase Refinement Phase Evaluation Phase Maintenance and Evolution Phase Related Work Skeletal Methodology KACTUS Methontology Formal Tools of Ontological Analysis Conclusion 45 4 Ontology Management: Storing, Aligning and Maintaining Ontologies 47 Michel Klein, Ying Ding, Dieter Fensel and Borys Omelayenko 4.1 The Requirement for Ontology Management Aligning Ontologies Why is Aligning Needed Aligning Annotated XML Documents Mapping Meta-ontology Mapping in OIL Supporting Ontology Change Ontologies are Changing Changes in Ontologies Involve Several Problems Change Management Organizing Ontologies Sesame Requirements Functionality of an Ontology Storage System Current Storage Systems Requirements for a Storage System Summary 69

9 Contents vii 5 Sesame: A Generic Architecture for Storing and Querying RDF and RDF Schema 71 Jeen Broekstra, Arjohn Kampman and Frank van Harmelen 5.1 The Need for an RDFS Query Language Querying at the Syntactic Level Querying at the Structure Level Querying at the Semantic Level Sesame Architecture The RQL Query module The Admin Module The RDF Export Module The SAIL API Experiences Application: On-To-Knowledge RDFS in Practice PostgreSQL and SAIL MySQL Future Work Transaction Rollback Support Versioning Support Adding and Extending Functional Modules DAML1OIL Support Conclusions 88 6 Generating Ontologies for the Semantic Web: OntoBuilder 91 R.H.P. Engels and T.Ch. Lech 6.1 Introduction OntoBuilder and its Relation to the CORPORUM System OntoExtract OntoWrapper and TableAnalyser Reading the Web Semantics on the Internet Problems with Retrieving Natural Language Texts from Documents Document Handling Normalization Multiple Discourses Document Class Categorization Writing Style Layout Issues Information Extraction Content-driven Versus Goal-driven Levels of Linguistic Analysis CognIT Vision Knowledge Generation from Natural Language Documents Syntax Versus Semantics Generating Semantic Structures Generating Ontologies from Textual Resources Visualization and Navigation 111

10 viii Contents 6.5 Issues in Using Automated Text Extraction for Ontology Building using IE on Web Resources 7 OntoEdit: Collaborative Engineering of Ontologies 117 York Sure, Michael Erdmann and Rudi Studer 7.1 Introduction Kick Off Phase Refinement Phase Transaction Management Locking Sub-trees of the Concept Hierarchy What Does Locking a Concept Mean? Evaluation Phase Analysis of Typical Queries Error Avoidance and Location Usage of Competency Questions Collaborative Evaluation Related Work Conclusion QuizRDF: Search Technology for the Semantic Web 133 John Davies, Richard Weeks and Uwe Krohn 8.1 Introduction Ontological Indexing Ontological Searching Alternative data models Indexing in the New Model Searching in the New Model Further Work Technical Enhancements Evaluation Concluding Remarks Spectacle 145 Christiaan Fluit, Herko ter Horst, Jos van der Meer, Marta Sabou and Peter Mika Introduction Spectacle Content Presentation Platform Ontologies in Spectacle Spectacle Architecture Ontology-based Mapping Methodology Information Entities Ontology Mapping Entity Rendering Navigation Specification Navigation Rendering Views User Profiles 152

11 Contents ix 9.5 Ontology-based Information Visualization Analysis Querying Navigation Summary: Semantics-based Web Presentations OntoShare: Evolving Ontologies in a Knowledge Sharing System 161 John Davies, Alistair Duke and Audrius Stonkus 10.1 Introduction Sharing and Retrieving Knowledge in OntoShare Sharing Knowledge in OntoShare Ontological Representation Retrieving Explicit Knowledge in OntoShare Creating Evolving Ontologies Expertise Location and Tacit Knowledge Sociotechnical Issues Tacit and Explicit Knowledge Flows Virtual Communities Evaluation and Further Work Concluding Remarks Ontology Middleware and Reasoning 179 Atanas Kiryakov, Kiril Simov and Damyan Ognyanov 11.1 Ontology Middleware: Features and Architecture Place in the On-To-Knowledge Architecture Terminology Tracking Changes, Versioning and Meta-information Related Work Requirements Versioning Model for RDF(S) Repositories History, Passing through Equivalent States Versions are Labelled States of the Repository Implementation Approach Meta-information Instance Reasoning for DAML + OIL Inference Services Functional Interfaces to adaml + OIL Reasoner Ontology-based Knowledge Management at Work: The Swiss Life Case Studies 197 Ulrich Reimer, Peter Brockhausen, Thorsten Lau and Jacqueline R. Reich 12.1 Introduction Skills Management What is Skills Management? SkiM: Skills Management at Swiss Life Architecture of SkiM SkiM as an Ontology-based Approach 203

12 x Contents Querying Facilities Evaluation and Outlook Automatically Extracting a Lightweight Ontology from Text Motivation Automatic Ontology Extraction Employing the Ontology for Querying Evaluation and Outlook Conclusions Field Experimenting with Semantic Web Tools in a Virtual Organization 219 Victor Iosif, Peter Mika, Rikard Larsson and Hans Akkermans 13.1 Introduction The EnerSearch Industrial Research Consortium as a Virtual Organization Why Might Semantic Web Methods Help? Design Considerations of Semantic Web Field Experiments Different Information Modes Different Target User Groups Different Individual Cognitive Styles Hypotheses to be Tested Experimental Set-up in a Virtual Organization Selecting Target Test Users Tools for Test Test Tasks and their Organization Experimental Procedure Determining What Data to Collect Evaluation Matrix and Measurements Technical and System Aspects of Semantic Web Experiments System Design Ontology Engineering, Population, Annotation Ontology-based Information Retrieval: What Does it Look Like? Ontology and Semantic Sitemaps Semantics-based Information Retrieval Some Lessons Learned A Future Perspective: Exploiting Peer-to-Peer and the Semantic Web for Knowledge Management 245 Dieter Fensel, Steffen Staab, Rudi Studer, Frank van Harmelen and John Davies 14.1 Introduction A Vision of Modern Knowledge Management Knowledge Integration Knowledge Categorization Context Awareness Personalization Knowledge Portal Construction Communities of Practice P2P Computing and its Implications for KM 250

13 Contents xi Virtual Organizations and their Impact elearning Systems The Knowledge Grid Intellectual Capital Valuation A Vision of Ontologies: Dynamic Networks of Meaning Ontologies or How to Escape a Paradox Heterogeneity in Space: Ontology as Networks of Meaning Development in Time: Living Ontologies Peer-2-Peer, Ontologies and Knowledge Shortcomings of Peer-2-Peer and Ontologies as Isolated Paradigms Challenges in Integrating Peer-2-Peer and Ontologies Conclusions P2P for Knowledge Management P2P for Ontologies Ontologies for P2P and Knowledge Management Community Building Conclusions: Ontology-driven Knowledge Management Towards the Semantic Web? 265 John Davies, Dieter Fensel and Frank van Harmelen References 267 Index 281

15 Foreword Knowledge is Power Again! J. Hendler, University of Maryland More than 30 years ago, ACM Turing Award winner, Ed Feigenbaum, heralded a revolution in business computing under the banner knowledge is power. With this slogan, Feigenbaum brought domain-specific expert systems to the attention of the computing world. Now deployed in shrinkwrapped tax preparation programs, embedded in one of the world s best selling software products, and estimated to be in use by over two-thirds of Fortune 500 companies, the expert system gains its power by the use of the specific knowledge of a domain that is encoded in its rules be it rules about tax laws, rules about the spelling of words, or the specific business rules dictating how your market sector operates. In all these systems, this special-purpose knowledge is where the power is derived. In the past decade, however, a new agenda has been evolving as part of research in what is now known as the Semantic Web. This approach might also be called knowledge is power, but with a significantly different metaphor. Where Feigenbaum envisioned power akin to the power of a sledgehammer, the new paradigm makes knowledge akin to the power flowing through the electrical grid. Rather than the centralized power coming from carefully engineered knowledge bases aimed at specific applications, the new power flows through the routers of the Internet, as electricity flows through the wires in your wall. Knowledge, in this view, becomes as distributed, dynamic and ubiquitous as the power flowing into the lamp by which you are reading these words. The Semantic Web vision, per se, is rightly attributed to Tim Berners-Lee, inventor of the web and coiner of the term Semantic Web, but he was not the first or only one to realize the strength of the new knowledge is power metaphor. A small group of researchers, branching out from the traditional confines of knowledge representation in Artificial Intelligence, were talking about knowledge servers, semantic engines, ontology management systems, and other approaches to ubiquitous knowledge before the web even came into being. However, with the expanding impact of Berners-Lee s World Wide Web, the

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