A Critical View of RDF: Summary o RDF has its idiosyncrasies and is not an optimal modeling language but o It is already a de facto standard o It has sufficient expressive power At least as for more layers to build on top o Using RDF offers the benefit that information maps unambiguously to a model 26 Chapter 3 A Semantic Web primer
Chapter 3 A Semantic Web Primer 26 A Critical View of RDF: Summary ⚫ RDF has its idiosyncrasies and is not an optimal modeling language but ⚫ It is already a de facto standard ⚫ It has sufficient expressive power – At least as for more layers to build on top ⚫ Using RDF offers the benefit that information maps unambiguously to a model
Lecture Outline 1. Basic Ideas of rdf 2. XML-based Syntax of RDF 3. Basic Concepts of RdF Schema 4. The Language of rdf Schema 5. The Namespaces of RdF and rdf Schema 6. Axiomatic Semantics for rdf and rdfS 7. Direct Semantics based on Inference rules 8. Querying of RDF/RDFS Documents using RQL 27 Chapter 3 A Semantic Web primer
Chapter 3 A Semantic Web Primer 27 Lecture Outline 1. Basic Ideas of RDF 2. XML-based Syntax of RDF 3. Basic Concepts of RDF Schema 4. Τhe Language of RDF Schema 5. The Namespaces of RDF and RDF Schema 6. Axiomatic Semantics for RDF and RDFS 7. Direct Semantics based on Inference Rules 8. Querying of RDF/RDFS Documents using RQL
XML-Based Syntax of RDF e An rdf document consists of an rdf rde element The content of that element is a number of descriptions o Namespace mechanism is used Disambiguation Namespaces are expected to be rdF documents defining resources that can be reused Large, distributed collections of knowledge 28 Chapter 3 A Semantic Web primer
Chapter 3 A Semantic Web Primer 28 XML-Based Syntax of RDF ⚫ An RDF document consists of an rdf:RDF element – The content of that element is a number of descriptions ⚫ A namespace mechanism is used – Disambiguation – Namespaces are expected to be RDF documents defining resources that can be reused – Large, distributed collections of knowledge
Example of University Courses <rdf: rdF xmins:rdf="http://www.w3.org/1999/0222-rdf-syntax-ns#f xmins:xsd="http://www.w3.org/2001/xlmschema# xminsunishttp://www.mydomain.org/uni-ns> <rdf: Description rdf: about=949318"> <uni: name>David Billington</uni: name> <uni title> Associate Professor/uni: title> <uni: age rdf: datatype="&xsd: integer">27<uni:age> </rdf: Description> 29 Chapter 3 A Semantic Web primer
Chapter 3 A Semantic Web Primer 29 Example of University Courses <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:xsd="http://www.w3.org/2001/XLMSchema#" xmlns:uni="http://www.mydomain.org/uni-ns"> <rdf:Description rdf:about="949318"> <uni:name>David Billington</uni:name> <uni:title>Associate Professor</uni:title> <uni:age rdf:datatype="&xsd:integer">27<uni:age> </rdf:Description>
Example of University Courses(2) <rdf: Description rdf: about=cIT1111"> <uni: course Name>Discrete Maths</uni: courseName> <uni: is TaughtBy>David Billington</uni: isTaughtBy> </rdf: Description> <rdf: Description rdf: about="CIT2112> <uni: course Name>Programming ll</uni courseName> <uni: is TaughtBy> Michael Maher</uni: is TaughtBy> </rdf: Description> </rdf: RDF 30 Chapter 3 A Semantic Web primer
Chapter 3 A Semantic Web Primer 30 Example of University Courses (2) <rdf:Description rdf:about="CIT1111"> <uni:courseName>Discrete Maths</uni:courseName> <uni:isTaughtBy>David Billington</uni:isTaughtBy> </rdf:Description> <rdf:Description rdf:about="CIT2112"> <uni:courseName>Programming III</uni:courseName> <uni:isTaughtBy>Michael Maher</uni:isTaughtBy> </rdf:Description> </rdf:RDF>