Preface -- 1 Introduction: Envisioning Semantic Information Spaces -- Part A Propaedeutics - Organizing, Representing, and Exploring Knowledge -- 2 Indexing and Knowledge Organization -- 2.1 Knowledge Organization Systems as Indexing Languages -- 2.1.1 Building Elements: Entities and Terms -- 2.1.2 Structural Elements: Intrasystem Relations -- 2.1.3 Result Elements: Indexates -- 2.2 Standards and Frameworks -- 2.2.1 ISO 25964: Thesauri and Interoperability with other Vocabularies -- 2.2.2 Functional Requirements for Subject Authority Data (FRSAD) -- 3 Semantic Technologies for Knowledge Representation -- 3.1 Web-based Representation Languages -- 3.1.1 XML -- 3.1.2 RDF/RDFS -- 3.1.3 OWL -- 3.2 Application-based Representation Languages -- 3.2.1 XTM -- 3.2.2 SKOS -- 4 Information Retrieval and Knowledge Exploration -- 4.1 Information Retrieval Essentials -- 4.1.1 Exact Match Paradigm -- 4.1.2 Partial Match Paradigm -- 4.2 Measuring Effectiveness in Information Retrieval -- 4.3 From Retrieving to Exploring -- 4.3.1 String-based Retrieval Processes -- 4.3.2 Conceptual Retrieval Process -- 4.3.3 Conceptual Exploration Processes -- 4.3.4 Topical Exploration Processes -- 4.4 From Homogeneous to Heterogeneous Information Spaces -- Part B Status quo - Handling Heterogeneity in Indexing and Retrieval -- 5 Approaches to Handle Heterogeneity -- 5.1 Citation Pearl Growing -- 5.2 Modeling Multilingual Indexing Languages -- 5.3 Establishing Semantic Interoperability between Indexing Languages -- 5.3.1 Structural Models -- 5.3.2 Mapping Levels -- 5.3.3 Vocabulary Linking Projects -- 6 Problems with Establishing Semantic Interoperability -- 6.1 Conceptual Interoperability between Entities of Indexing Languages -- 6.1.1 Focused and Comprehensive Mapping -- 6.1.2 Conceptual Identity and Semantic Congruence.

6.2 Equivalent Intersystem Relationships -- 6.2.1 Intersystem Relations Compared to Intrasystem Relations -- 6.2.2 Interoperability and Search Tactics -- 6.2.3 Specified Intersystem Relationships -- 6.2.4 Conceptual Interoperability between Indexing Results -- 6.2.5 Directedness of Intersystem Relationships -- Part C Vision - Ontology-based Indexing and Retrieval -- 7 Formalization in Indexing Languages -- 7.1 Introduction and Objectives -- 7.2 Common Characteristics and Differences between Indexing Languages and Formal Knowledge Representation -- 7.3 Prerequisites for an Ontology-based Indexing -- 7.3.1 Semantic Relations and Inferred Document Sets -- 7.3.2 Facets and Inferences -- 8 Typification of Semantic Relations -- 8.1 Inventories of Typed relations -- 8.2 Typed Relations and their Benefit for Indexing and Retrieval -- 8.3 Examples of the Benefit of Typed Relations for the Retrieval Process -- 8.3.1 Example 1: Aspect-oriented Specification of the Generic Hierarchy Relation -- 8.3.2 Example 2: Typed Relations of a Topic Map built from the ASIST Thesaurus -- 8.3.3 Example 3: Degrees of Determinacy -- 9 Inferences in Retrieval Processes -- 9.1 Inferences of Level 1 -- 9.1.1 Hierarchical Relationships -- 9.1.2 Associative Relationships -- 9.1.3 Typification of the Synonymy/Equivalence Relationship -- 9.2 Inferences of Level 2 and of Higher Levels, Transitivity -- 9.2.1 Hierarchical Relationships -- 9.2.2 Unspecific Associative Relationships -- 9.2.3 Typification of Associative Relationships -- 9.3 Inferences by Combining Different Types of Relationships -- 9.3.1 Synonymy Relation with Hierarchical Relationships -- 9.3.2 Chronological Relation with Hierarchical Relationships -- 9.3.3 Transitions from Associative Relationships to a Hierarchical Structure.

9.3.4 Transitions from a Hierarchical Structure to Associative Relationships -- 9.3.5 Transitivity for Combinations of Typed Associative Relationships -- 10 Semantic Interoperability and Inferences -- 10.1 Conditions for Entity-based Interoperability -- 10.2 Models of Semantic Interoperability -- 10.2.1 Ontological Spine and Satellite Ontologies -- 10.2.2 Degrees of Determinacy and Interoperability -- 10.2.3 Entity-based Interoperability and Facets -- 10.3 Perspective: Ontology-based Indexing and Retrieval -- 11 Remaining Research Questions -- 11.1 Questions of Modeling -- 11.2 Questions of Procedure -- 11.3 Questions of Technology and Implementation -- Part D Appendices -- Systematic Glossary -- Abbreviations -- List of figures -- List of tables -- References -- Index.