TOWARDS THE SEMANTIC WEB

Contents
Foreword xiii
Biographies xv
List of Contributors xix
Acknowledgments xxi
1 Introduction 1
John Davies, Dieter Fensel and Frank van Harmelen
1.1 The Semantic Web and Knowledge Management 2
1.2 The Role of Ontologies 4
1.3 An Architecture for Semantic Web-based Knowledge Management 5
1.3.1 Knowledge Acquisition 5
1.3.2 Knowledge Representation 6
1.3.3 Knowledge Maintenance 7
1.3.4 Knowledge Use 7
1.4 Tools for Semantic Web-based Knowledge Management 7
1.4.1 Knowledge Acquisition 8
1.4.2 Knowledge Representation 8
1.4.3 Knowledge Maintenance 8
1.4.4 Knowledge Use 8
2 OIL and DAML1OIL: Ontology Languages for the Semantic Web 11
Dieter Fensel, Frank van Harmelen and Ian Horrocks
2.1 Introduction 11
2.2 The Semantic Web Pyramid of Languages 12
2.2.1 XML for Data Exchange 12
2.2.2 RDF for Assertions 13
2.2.3 RDF Schema for Simple Ontologies 14
2.3 Design Rationale for OIL 15
2.3.1 Frame-based Systems 16
2.3.2 Description Logics 17
2.3.3 Web Standards: XML and RDF 17
2.4 OIL Language Constructs 17
2.4.1 A Simple Example in OIL 18
2.5 Different Syntactic Forms 20
2.6 Language Layering 23
2.7 Semantics 26
2.8 From OIL to DAML1OIL 26
2.8.1 Integration with RDFS 26
2.8.2 Treatment of Individuals 29
2.8.3 DAML1OIL Data Types 29
2.9 Experiences and Future Developments 31
3 A Methodology for Ontology-based Knowledge Management 33
York Sure and Rudi Studer
3.1 Introduction 33
3.2 Feasibility Study 34
3.3 Kick Off Phase 38
3.4 Refinement Phase 41
3.5 Evaluation Phase 41
3.6 Maintenance and Evolution Phase 42
3.7 Related Work 42
3.7.1 Skeletal Methodology 43
3.7.2 KACTUS 44
3.7.3 Methontology 44
3.7.4 Formal Tools of Ontological Analysis 45
3.8 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 47
4.2 Aligning Ontologies 48
4.2.1 Why is Aligning Needed 48
4.2.2 Aligning Annotated XML Documents 49
4.2.3 Mapping Meta-ontology 50
4.2.4 Mapping in OIL 53
4.3 Supporting Ontology Change 54
4.3.1 Ontologies are Changing 54
4.3.2 Changes in Ontologies Involve Several Problems 55
4.3.3 Change Management 58
4.4 Organizing Ontologies 61
4.4.1 Sesame Requirements 62
4.4.2 Functionality of an Ontology Storage System 62
4.4.3 Current Storage Systems 64
4.4.4 Requirements for a Storage System 66
4.5 Summary 69
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 72
5.1.1 Querying at the Syntactic Level 72
5.1.2 Querying at the Structure Level 73
5.1.3 Querying at the Semantic Level 75
5.2 Sesame Architecture 76
5.2.1 The RQL Query module 78
5.2.2 The Admin Module 79
5.2.3 The RDF Export Module 80
5.3 The SAIL API 80
5.4 Experiences 82
5.4.1 Application: On-To-Knowledge 82
5.4.2 RDFS in Practice 84
5.4.3 PostgreSQL and SAIL 84
5.4.4 MySQL 86
5.5 Future Work 87
5.5.1 Transaction Rollback Support 87
5.5.2 Versioning Support 88
5.5.3 Adding and Extending Functional Modules 88
5.5.4 DAML1OIL Support 88
5.6 Conclusions 88
6 Generating Ontologies for the Semantic Web: OntoBuilder 91
R.H.P. Engels and T.Ch. Lech
6.1 Introduction 91
6.1.1 OntoBuilder and its Relation to the CORPORUM System 92
6.1.2 OntoExtract 93
6.1.3 OntoWrapper and TableAnalyser 96
6.2 Reading the Web 97
6.2.1 Semantics on the Internet 97
6.2.2 Problems with Retrieving Natural Language Texts from Documents 99
6.2.3 Document Handling 100
6.2.4 Normalization 100
6.2.5 Multiple Discourses 101
6.2.6 Document Class Categorization 102
6.2.7 Writing Style 102
6.2.8 Layout Issues 102
6.3 Information Extraction 103
6.3.1 Content-driven Versus Goal-driven 104
6.3.2 Levels of Linguistic Analysis 104
6.3.3 CognIT Vision 107
6.4 Knowledge Generation from Natural Language Documents 108
6.4.1 Syntax Versus Semantics 108
6.4.2 Generating Semantic Structures 109
6.4.3 Generating Ontologies from Textual Resources 110
6.4.4 Visualization and Navigation 111
6.5 Issues in Using Automated Text Extraction for Ontology Building using IE
on Web Resources 111
7 OntoEdit: Collaborative Engineering of Ontologies 117
York Sure, Michael Erdmann and Rudi Studer
7.1 Introduction 117
7.2 Kick Off Phase 118
7.3 Refinement Phase 123
7.3.1 Transaction Management 124
7.3.2 Locking Sub-trees of the Concept Hierarchy 126
7.3.3 What Does Locking a Concept Mean? 127
7.4 Evaluation Phase 128
7.4.1 Analysis of Typical Queries 128
7.4.2 Error Avoidance and Location 129
7.4.3 Usage of Competency Questions 129
7.4.4 Collaborative Evaluation 130
7.5 Related Work 130
7.6 Conclusion 131
8 QuizRDF: Search Technology for the Semantic Web 133
John Davies, Richard Weeks and Uwe Krohn
8.1 Introduction 133
8.2 Ontological Indexing 135
8.3 Ontological Searching 138
8.4 Alternative data models 141
8.4.1 Indexing in the New Model 141
8.4.2 Searching in the New Model 142
8.5 Further Work 142
8.5.1 Technical Enhancements 142
8.5.2 Evaluation 143
8.6 Concluding Remarks 143
9 Spectacle 145
Christiaan Fluit, Herko ter Horst, Jos van der Meer, Marta Sabou
and Peter Mika
9.1 Introduction 145
9.2 Spectacle Content Presentation Platform 145
9.2.1 Ontologies in Spectacle 146
9.3 Spectacle Architecture 147
9.4 Ontology-based Mapping Methodology 147
9.4.1 Information Entities 149
9.4.2 Ontology Mapping 149
9.4.3 Entity Rendering 150
9.4.4 Navigation Specification 150
9.4.5 Navigation Rendering 151
9.4.6 Views 152
9.4.7 User Profiles 152
9.5 Ontology-based Information Visualization 153
9.5.1 Analysis 153
9.5.2 Querying 156
9.5.3 Navigation 158
9.6 Summary: Semantics-based Web Presentations 159
10 OntoShare: Evolving Ontologies in a Knowledge Sharing System 161
John Davies, Alistair Duke and Audrius Stonkus
10.1 Introduction 161
10.2 Sharing and Retrieving Knowledge in OntoShare 162
10.2.1 Sharing Knowledge in OntoShare 163
10.2.2 Ontological Representation 164
10.2.3 Retrieving Explicit Knowledge in OntoShare 167
10.3 Creating Evolving Ontologies 169
10.4 Expertise Location and Tacit Knowledge 170
10.5 Sociotechnical Issues 172
10.5.1 Tacit and Explicit Knowledge Flows 172
10.5.2 Virtual Communities 173
10.6 Evaluation and Further Work 175
10.7 Concluding Remarks 176
11 Ontology Middleware and Reasoning 179
Atanas Kiryakov, Kiril Simov and Damyan Ognyanov
11.1 Ontology Middleware: Features and Architecture 179
11.1.1 Place in the On-To-Knowledge Architecture 181
11.1.2 Terminology 182
11.2 Tracking Changes, Versioning and Meta-information 183
11.2.1 Related Work 184
11.2.2 Requirements 184
11.3 Versioning Model for RDF(S) Repositories 185
11.3.1 History, Passing through Equivalent States 188
11.3.2 Versions are Labelled States of the Repository 188
11.3.3 Implementation Approach 188
11.3.4 Meta-information 190
11.4 Instance Reasoning for DAML1OIL 192
11.4.1 Inference Services 194
11.4.2 Functional Interfaces to a DAML1OIL Reasoner 195
12 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 197
12.2 Skills Management 198
12.2.1 What is Skills Management? 198
12.2.2 SkiM: Skills Management at Swiss Life 200
12.2.3 Architecture of SkiM 202
12.2.4 SkiM as an Ontology-based Approach 203
12.2.5 Querying Facilities 207
12.2.6 Evaluation and Outlook 208
12.3 Automatically Extracting a ‘Lightweight Ontology’ from Text 209
12.3.1 Motivation 209
12.3.2 Automatic Ontology Extraction 210
12.3.3 Employing the Ontology for Querying 213
12.3.4 Evaluation and Outlook 215
12.4 Conclusions 217
13 Field Experimenting with Semantic Web Tools in a Virtual Organization 219
Victor Iosif, Peter Mika, Rikard Larsson and Hans Akkermans
13.1 Introduction 219
13.2 The EnerSearch Industrial Research Consortium as a Virtual Organization 219
13.3 Why Might Semantic Web Methods Help? 222
13.4 Design Considerations of Semantic Web Field Experiments 223
13.4.1 Different Information Modes 224
13.4.2 Different Target User Groups 224
13.4.3 Different Individual Cognitive Styles 225
13.4.4 Hypotheses to be Tested 228
13.5 Experimental Set-up in a Virtual Organization 229
13.5.1 Selecting Target Test Users 229
13.5.2 Tools for Test 230
13.5.3 Test Tasks and their Organization 230
13.5.4 Experimental Procedure 231
13.5.5 Determining What Data to Collect 232
13.5.6 Evaluation Matrix and Measurements 233
13.6 Technical and System Aspects of Semantic Web Experiments 234
13.6.1 System Design 234
13.6.2 Ontology Engineering, Population, Annotation 235
13.7 Ontology-based Information Retrieval: What Does it Look Like? 236
13.7.1 Ontology and Semantic Sitemaps 236
13.7.2 Semantics-based Information Retrieval 239
13.8 Some Lessons Learned 241
14 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 245
14.2 A Vision of Modern Knowledge Management 247
14.2.1 Knowledge Integration 247
14.2.2 Knowledge Categorization 247
14.2.3 Context Awareness 248
14.2.4 Personalization 248
14.2.5 Knowledge Portal Construction 249
14.2.6 Communities of Practice 249
14.2.7 P2P Computing and its Implications for KM 250
14.2.8 Virtual Organizations and their Impact 251
14.2.9 eLearning Systems 251
14.2.10 The Knowledge Grid 251
14.2.11 Intellectual Capital Valuation 252
14.3 A Vision of Ontologies: Dynamic Networks of Meaning 252
14.3.1 Ontologies or How to Escape a Paradox 253
14.3.2 Heterogeneity in Space: Ontology as Networks of Meaning 254
14.3.3 Development in Time: Living Ontologies 255
14.4 Peer-2-Peer, Ontologies and Knowledge 256
14.4.1 Shortcomings of Peer-2-Peer and Ontologies as Isolated Paradigms
256
14.4.2 Challenges in Integrating Peer-2-Peer and Ontologies 258
14.5 Conclusions 263
14.5.1 P2P for Knowledge Management 263
14.5.2 P2P for Ontologies 263
14.5.3 Ontologies for P2P and Knowledge Management 264
14.5.4 Community Building 264
15 Conclusions: Ontology-driven Knowledge Management – Towards the
Semantic Web? 265
John Davies, Dieter Fensel and Frank van Harmelen
References 267
Index 281

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