Semantic Web for the Working Ontologist (eBook)

Front Cover 1
Semantic Web for the Working Ontologist Modeling in RDF, RDFS and OWL 4
Copyright Page 5
Contents 8
Preface 14
About the Authors 18
Chapter 1: What Is the Semantic Web? 20
What Is a Web? 20
Smart Web, Dumb Web 21
Smart Web Applications 22
A Connected Web Is a Smarter Web 23
Semantic Data 24
A Distributed Web of Data 25
Features of a Semantic Web 26
What about the Round-Worlders? 28
To Each Their Own 29
There's Always One More 30
Summary 31
Fundamental Concepts 32
Chapter 2: Semantic Modeling 34
Modeling for Human Communication 36
Explanation and Prediction 38
Mediating Variability 40
Variation and Classes 41
Variation and Layers 42
Expressivity in Modeling 45
Summary 47
Fundamental Concepts 48
Chapter 3: RDF-The Basis of the Semantic Web 50
Distributing Data Across the Web 51
Merging Data from Multiple Sources 55
Namespaces, URIs, and Identity 56
Expressing URIs in Print 59
Standard Namespaces 62
Identifiers in the RDF Namespace 63
Challenge: RDF and Tabular Data 64
Higher-Order Relationships 68
Alternatives for Serialization 70
N-Triples 70
Notation 3 RDF (N3) 71
RDF/XML 72
Blank Nodes 73
Ordered Information in RDF 75
Summary 75
Fundamental Concepts 76
Chapter 4: Semantic Web Application Architecture 78
RDF Parser/Serializer 79
Other Data Sources-Converters and Scrapers 80
RDF Store 83
RDF Data Standards and Interoperability of RDF Stores 85
RDF Query Engines and SPARQL 85
Comparison to Relational Queries 91
Application Code 92
RDF-Backed Web Portals 94
Data Federation 94
Summary 95
Fundamental Concepts 96
Chapter 5: RDF and Inferencing 98
Inference in the Semantic Web 99
Virtues of Inference-Based Semantics 101
Where Are the Smarts? 102
Asserted Triples versus Inferred Triples 104
When Does Inferencing Happen? 106
Inferencing as Glue 107
Summary 108
Fundamental Concepts 109
Chapter 6: RDF Schema 110
Schema Languages and their Functions 110
What Does it Mean? Semantics as Inference 112
The RDF Schema Language 114
Relationship Propagation through rdfs:subPropertyOf 114
Typing Data by Usage-rdfs:domain and rdfs:range 117
Combination of Domain and Range with rdfs:subClassOf 118
RDFS Modeling Combinations and Patterns 121
Set Intersection 121
Property Intersection 123
Set Union 124
Property Union 125
Property Transfer 125
Challenges 127
Term Reconciliation 127
Instance-Level Data Integration 129
Readable Labels with rdfs:label 129
Data Typing Based on Use 130
Filtering Undefined Data 134
RDFS and Knowledge Discovery 134
Modeling with Domains and Ranges 135
Multiple Domains/Ranges 135
Nonmodeling Properties in RDFS 139
Cross-Referencing Files: rdfs:seeAlso 139
Organizing Vocabularies: rdfs:isDefinedBy 140
Model Documentation: rdfs:comment 140
Summary 140
Fundamental Concepts 141
Chapter 7: RDFS-Plus 142
Inverse 143
Challenge: Integrating Data that Do Not Want to Be Integrated 144
Challenge: Using the Modeling Language to Extend the Modeling Language 146
Challenge: The Marriage of Shakespeare 148
Symmetric Properties 148
Using OWL to Extend OWL 149
Transitivity 150
Challenge: Relating Parents to Ancestors 151
Challenge: Layers of Relationships 152
Managing Networks of Dependencies 153
Equivalence 158
Equivalent Classes 160
Equivalent Properties 161
Same Individuals 162
Challenge: Merging Data from Different Databases 165
Computing Sameness-Functional Properties 168
Functional Properties 169
Inverse Functional Properties 170
Combining Functional and Inverse Functional Properties 173
A Few More Constructs 174
Summary 175
Fundamental Concepts 176
Chapter 8: Using RDFS-Plus in the Wild 178
SKOS 178
Semantic Relations in SKOS 182
Meaning of Semantic Relations 184
Special Purpose Inference 185
Published Subject Indicators 187
SKOS in Action 187
FOAF 188
People and Agents 189
Names in FOAF 190
Nicknames and Online Names 190
Online Persona 191
Groups of People 192
Things People Make and Do 193
Identity in FOAF 194
It's Not What You Know, It's Who You Know 195
Summary 196
Fundamental Concepts 197
Chapter 9: Basic OWL 198
Restrictions 198
Example: Questions and Answers 199
Adding "Restrictions" 202
Kinds of Restrictions 203
Challenge Problems 215
Challenge: Local Restriction of Ranges 215
Challenge: Filtering Data Based on Explicit Type 217
Challenge: Relationship Transfer in SKOS 221
Relationship Transfer in FOAF 223
Alternative Descriptions of Restrictions 228
Summary 229
Fundamental Concepts 230
Chapter 10: Counting and Sets in OWL 232
Unions and Intersections 233
Closing the World 235
Enumerating Sets with owl:oneOf 235
Differentiating Individuals with owl:differentFrom 237
Differentiating Multiple Individuals 238
Cardinality 241
Small Cardinality Limits 244
Set Complement 245
Disjoint Sets 247
Prerequisites Revisited 250
No Prerequisites 251
Counting Prerequisites 252
Guarantees of Existence 253
Contradictions 254
Unsatisfiable Classes 256
Propagation of Unsatisfiable Classes 256
Inferring Class Relationships 257
Reasoning with Individuals and with Classes 262
Summary 263
Fundamental Concepts 264
Chapter 11: Using OWL in the Wild 266
The Federal Enterprise Architecture Reference Model Ontology 267
Reference Models and Composability 268
Resolving Ambiguity in the Model: Sets Versus Individuals 270
Constraints Between Models 272
OWL and Composition 274
owl:Ontology 274
owl:imports 275
Advantages of the Modeling Approach 276
The National Cancer Institute Ontology 277
Requirements of the NCI Ontology 278
Upper-Level Classes 280
Describing Classes in the NCI Ontology 285
Instance-Level Inferencing in the NCI Ontology 286
Summary 288
Fundamental Concepts 289
Chapter 12: Good and Bad Modeling Practices 290
Getting Started 290
Know What You Want 291
Inference Is Key 292
Modeling for Reuse 293
Insightful Names Versus Wishful Names 293
Keeping Track of Classes and Individuals 294
Model Testing 296
Common Modeling Errors 296
Rampant Classism (Antipattern) 296
Exclusivity (Antipattern) 301
Objectification (Antipattern) 304
Managing Identifiers for Classes (Antipattern) 307
Creeping Conceptualization (Antipattern) 308
Summary 309
Fundamental Concepts 310
Chapter 13: OWL Levels and Logic 312
OWL Full versus OWL DL 313
Provable Models 
313 
Class/Individual Separation 317
InverseFunctional Datatypes 317
OWL Lite 318
Other Subsets of OWL 318
Beyond OWL 1.0 319
Metamodeling 319
Multipart Properties 320
Qualified Cardinality 321
Multiple Inverse Functional Properties 321
Rules 322
Summary 323
Fundamental Concepts 323
Chapter 14: Conclusions 326
Appendix: Frequently Asked Questions 332
Further Reading 336
Index 340