Chapter 1 Introduction 1.1 Semantic Web and Ontologies 1.2 Motivations 1.2.1 Fuzziness of Concepts 1.2.2 Typicality of Objects in Concepts 1.2.3 Context and Its Efiect on Reasoning 1.3 Our Work 1.3.1 Objectives 1.3.2 Contributions 1.4 Structure of the Book References Chapter 2 Knowledge Representation on the Wleb 2.1 Semantic Web 2.2 Ontologies 2.3 Description Logics References Chapter 3 Concepts and Categorization from a Psychological Perspective 3.1 Theory of Concepts 3.1.1 Classical View 3.1.2 Prototype View 3.1.3 Other Views 3.2 Membership versus Typicality 3.3 Similarity Between Concepts 3.4 Context and Context Efiects References Chapter 4 Modeling Uncertainty in Knowledge Representation 4.1 Fuzzy Set Theory 4.2 Uncertainty in Ontologies and Description Logics 4.3 Semantic Similarity 4.4 Contextual Reasoning 4.5 Summary References Chapter 5 Fuzzy Ontology:A First Formal Model 5.1 Rationale 5.2 Concepts and Properties 5.3 Subsumption of Concepts 5.4 Object Membership of an Individual in a Concept 5.5 Prototype Vector and Typicality 5.6 An Example 5.7 Properties of the Proposed Model 5.7.1 Object Membership 5.7.2 Typicality 5.8 On Object Membership and Typicality 5.9 Summary References Chapter 6 A More General Ontology Model with ObjectMembership and Typicality 6.1 Motivation 6.2 Limitations of Previous Models 6.2.1 Limitation of Previous Modds in Measuring Object Membership 6.2.2 Limitations of Previous Models in Measuring Object Typicality 6.3 A Better Conceptual Model of Fuzzy Ontology 6.3.1 A Novel Fuzzy Ontology Model 6.3.2 Two Kinds of Measurements of Objects Possessing Properties 6.3.3 Concepts Represented by N-Properties and L-Properties 6.4 Fuzzy Membership of Objects in Concepts 6.4.1 Measuring Degrees of Objects Possessing Defining Properties of Concepts …… Chapter 7 Context-aware Object Typicality Measurement in Fuzzy Ontology Chapter 8 Object Membership with Property Importance and Property Priority Chapter 9 Applications Chapter 10 Conclusions and Future Work Index