| Preface | 6 |
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| About the book | 6 |
| The success of the information society | 6 |
| The remaining problems | 7 |
| Intended readership | 9 |
| Organization of the Book | 9 |
| Acknowledgements | 11 |
| Contents | 13 |
|---|
| Part I Information sharing and ontologies | 18 |
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| 1 Semantic integration | 19 |
| 1.1 Syntactic standards | 20 |
| 1.1.1 HTML: visualizing information | 20 |
| 1.1.2 XML: exchanging information | 21 |
| 1.1.3 RDF: a data model for meta-information | 22 |
| 1.1.4 The roles of XML and RDF | 24 |
| 1.2 The Problem of Heterogeneity | 26 |
| 1.2.1 Structural Conflicts | 26 |
| 1.2.2 Semantic Conflicts | 28 |
| 1.3 Handling information semantics | 30 |
| 1.3.1 Semantics from structure | 31 |
| 1.3.2 Semantics from text | 32 |
| 1.3.3 The need for explicit semantics | 33 |
| 1.4 Representing and comparing semantics | 35 |
| 1.4.1 Names and labels | 36 |
| 1.4.2 Term networks | 36 |
| 1.4.3 Concept lattices | 37 |
| 1.4.4 Features and constraints | 38 |
| 1.5 Conclusion | 39 |
| Further Reading | 39 |
| 2 Ontology-based information sharing | 40 |
| 2.1 Ontologies | 40 |
| 2.1.1 Shared vocabularies and conceptualizations | 41 |
| 2.1.2 Speci.cation of context knowledge | 42 |
| 2.1.3 Beneficial applications | 44 |
| 2.2 Ontologies in information integration | 46 |
| 2.2.1 Content explication | 46 |
| 2.2.2 Additional roles of ontologies | 49 |
| 2.3 A framework for information sharing | 51 |
| 2.4 A translation approach to ontology alignment | 53 |
| 2.4.1 The translation process | 54 |
| 2.4.2 Required infrastructure | 55 |
| 2.5 Conclusions | 57 |
| 3 Ontology languages for the Semantic Web | 60 |
| 3.1 An abstract view | 60 |
| 3.2 Two Semantic Web ontology languages | 62 |
| 3.2.1 RDF Schema | 64 |
| 3.2.2 OWL Lite | 65 |
| 3.2.3 OWL DL | 67 |
| 3.2.4 OWL Full | 68 |
| 3.2.5 Computational Complexity | 69 |
| 3.2.6 Simple relations between ontologies | 69 |
| 3.3 Other Web-based ontology languages | 73 |
| 3.3.1 Languages for expressing ontology mappings | 75 |
| 3.4 Conclusions | 76 |
| Part II Creating ontologies and metadata | 77 |
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| 4 Ontology creation | 78 |
| 4.1 Ontological engineering | 79 |
| 4.2 Building an ontology infrastructure for Information sharing | 81 |
| 4.3 Applying the approach | 83 |
| 4.3.1 The task to be solved | 84 |
| 4.3.2 The Information Sources | 85 |
| 4.3.3 Sources of knowledge | 86 |
| 4.4 An example walkthrough | 89 |
| 4.5 Conclusions | 95 |
| 5 Metadata generation | 97 |
| 5.1 The role of metadata | 98 |
| 5.1.1 Use of metadata | 99 |
| 5.1.2 Problems with metadata management | 100 |
| 5.2 The WebMaster approach | 102 |
| 5.2.1 BUISY: A Web based environmental information system | 102 |
| 5.2.2 The WebMaster Workbench | 103 |
| 5.2.3 Applying WebMaster to the BUISY system | 105 |
| 5.3 Learning classification rules | 109 |
| 5.3.1 Inductive logic programming | 110 |
| 5.3.2 Applying inductive logic programming | 112 |
| 5.3.3 Learning experiments | 114 |
| 5.3.4 Extracted classi.cation rules | 118 |
| 5.4 Ontology deployment | 122 |
| 5.4.1 Generating ontology-based metadata | 123 |
| 5.4.2 Using ontology-based metadata | 124 |
| 5.5 Conclusions | 126 |
| Part III Retrieval, integration and querying | 128 |
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| 6 Retrieval and Integration | 129 |
| 6.1 Semantic integration | 130 |
| 6.1.1 Ontology heterogeneity | 130 |
| 6.1.2 Multiple systems and translatability | 132 |
| 6.1.3 Approximate re-classification | 133 |
| 6.2 Concept-based filtering | 135 |
| 6.2.1 The idea of query-rewriting | 136 |
| 6.2.2 Boolean concept expressions | 137 |
| 6.2.3 Query re-writing | 139 |
| 6.3 Processing complex queries | 141 |
| 6.3.1 Queries as concepts | 142 |
| 6.3.2 Query relaxation | 144 |
| 6.4 Examples from a case study | 147 |
| 6.4.1 Concept approximations | 147 |
| 6.4.2 Query relaxation | 148 |
| 6.5 Conclusions | 150 |
| 7 Sharing statistical information | 152 |
| 7.1 The nature of statistical information | 153 |
| 7.1.1 Statistical metadata | 154 |
| 7.1.2 A basic ontology of statistics | 155 |
| 7.2 Modelling Statistics | 159 |
| 7.2.1 Statistics as views | 159 |
| 7.2.2 Connection with the domain | 160 |
| 7.3 Translation to Semantic Web languages | 164 |
| 7.3.1 Ontologies | 164 |
| 7.3.2 Description of information | 168 |
| 7.4 Retrieving statistical information | 171 |
| 7.5 Conclusions | 173 |
| 8 Spatially-related information | 175 |
| 8.1 Spatial representation and reasoning | 176 |
| 8.1.1 Levels of spatial abstraction | 176 |
| 8.1.2 Reasoning about spatial relations | 177 |
| 8.2 Ontologies and spatial relevance | 178 |
| 8.2.1 Defining Spatial Relevance | 179 |
| 8.2.2 Combined spatial and terminological matching | 180 |
| 8.2.3 Limitations | 182 |
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