Lesson 4: RDF Schema (Resource Description Framework)
 Questions & Answers
- What is XML Schema?
- XML Schema is a XML schema language (like RELAX NG).
- See W3C XML Schema Primer.
- XML Schema instances are called XML Schema Definition (XSD).
- XML Schema Definitions are used for validation of XML documents (like DTD files).
- XSD is also an initialism for XML Schema Datatypes.
- XML Schema Datatypes can be used in RDF2Go, the namespace is called XSD, too.
- What is RDF Schema?
- RDF Schema (RDFS) is an extension of the RDF-Vocabulary, adding definitions of classes and properties that may be used to describe classes, properties and other resources.
- You will often see RDFS files with a class ontology/vocabulary used by an instance RDF with many many instances of these classes. One example is the FOAF vocabulary (RDFS) and the many foaf files which contain descriptive information about foaf:Person instances.
- How do you find an existing RDF Schema?
- What is OWL?
- OWL stands for Web Ontology Language
- OWL is the successor of DAML+OIL
- OWL comes in 3 flavors: Lite, DL, Full
- See W3C OWL Features Overview for further information
- OWL reasoning is not yet supported by RDF2Go.
- What is reasoning/inferencing?
- reasoning and inferencing share the same meaning
- reasoning in some semantics creates additional statements by logical deduction.
- imagine a transitive relation "knows" and some objects a,b,c. If a knows b and b knows c, a reasoner which can handle the transitivity of relations will produce the statement "a knows c".