RDF Schema

All you want to know about RDF Schema

Part of a series on
Semantic Web
Background

The World Wide Web, The Internet, Databases, Semantic networks, Knowledge bases, Ontologies
Sub-topics

Linked Data, Data Web, Hyperdata, Dereferenceable URIs, Ontologies, Rule bases, Data Spaces
Related Topics

Web 2.0, Web 3.0, Plain Old Semantic HTML, Search engine optimization, Open Database Connectivity, References, Information architecture, Knowledge management, Topic Maps, XML, Description logic
Standards

W3C based
RDF, OWL, URI, HTTP, SPARQL, GRDDL, RDFS
Common Vocabularies
FOAF, SIOC, Dublin Core, SKOS
Semantic Annotation
RDFa, Microformats, eRDF
Rules
Rule Interchange Format, Semantic Web Rule Language
People

Tim Berners-Lee, James Hendler, Ora Lassila, Nigel Shadbolt, Wendy Hall, Kingsley Idehen, Dan Brickley, Libby Miller, Dave Beckett
Key Semantic-Web Organizations

W3C, WRSI, MIT, OpenLink Software, Talis Group, Oracle , ClearForest, University of Southampton, DERI

RDFS or RDF Schema is an extensible knowledge representation language, providing basic elements for the description of ontologies, otherwise called RDF vocabularies, intended to structure RDF resources. The first version was published by W3C in April 1998, and the final W3C recommendation was released in February 2004. Main RDFS components are included in the more expressive language OWL.

Contents

Main RDFS constructs

Classes and subclasses

  • rdfs:Class allows to declare a resource as a class for other resources.

Typical example of an rdfs:Class is foaf:Person in the FOAF vocabulary. An instance of foaf:Person is a resource linked to the class using an rdf:type predicate, such as in the following formal expression of the natural language sentence : 'John is a Person'.

ex:John rdf:type foaf:Person

The definition of rdfs:Class is recursive: rdfs:Class is the rdfs:Class of any rdfs:Class.

  • rdfs:subClassOf allows to declare hierarchies of classes.

For example, the following declares that 'Every Person is an Agent':

foaf:Person rdfs:subClassOf foaf:Agent

Hierarchies of classes support inheritance of a property domain and range (see definitions in next section) from a class to its subclasses.

Property domain and range

  • rdfs:domain of an rdf:property declares the class of the subject in a triple using this property as predicate.
  • rdfs:range of an rdf:property declares the class or datatype of the object in a triple using this property as predicate.

For example the following declarations are used to express that the property ex:employer is linking a subject which is a foaf:Person, to an object which is a foaf:Organization

ex:employer rdfs:domain foaf:Person

ex:employer rdfs:range foaf:Organization

Given the previous declarations, in the following triple, ex:John is necessarily a foaf:Person, and ex:CompanyX is necessarily a foaf:Organization

ex:John ex:employer ex:CompanyX

See also

  • SPARQL Query Language for RDF

External links

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Standards of the World Wide Web Consortium
Recommendations
Canonical XML · CDF · CGI · CSS · DOM · HTML · MathML · OWL · PLS · RDF · RDF Schema · SISR · SMIL · SOAP · SRGS · SSML · SVG · SPARQL · Timed Text · VoiceXML · WSDL · XForms · XHTML · XML · XML Base · XML Events · XML Information Set · XML Schema (W3C) · XML Signature · XPath · XPointer · XQuery · XSL Transformations · XSL-FO · XSL · XLink
Notes
Working Drafts
CCXML · CURIE · InkML · XFrames · XFDL · WICD  · XHTML+MathML+SVG · XBL · XProc · HTML 5
Retrieved from "http://en.wikipedia.org/wiki/RDF_Schema"

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