|Help TOC > PLCS technical description > Reference Data > OWL - Web Ontology Language|
|OWL - Web Ontology Language||Date: 2010/02/10 16:32:29
This is a brief overview of the subset of the OWL language used for defining the PLCS Reference Data and does not attempt to cover the entire language. OWL is an ontology modelling language layered over RDF (Resource Description Framework) that includes the following features:
OWL then pulls together the elements from these other W3C standards and adds more powerful concepts for defining vocabularies, set theory concepts, individuals and the rest. Because of this layering, when written as RDF/XML the XML Namespaces associated with these other standards appear in OWL XML documents.
There are three kinds of OWL specified in the standard: OWL Lite, OWL DL and OWL Full. These allow levels of implementation and serve as a series of (what are essentially) "conformance class" for such implementations. OWL DL builds on OWL Lite, and OWL Full builds on OWL DL. PLCS has, because of practical considerations, elected to use OWL DL. The “DL” in OWL DL is “Description Logic”. There are reasoners and inference engines that understand DL but far fewer understand OWL Full. The software tools supporting OWL can report whether the ontology is DL or not.
The core concepts in OWL used for specifying the PLCS Reference Data are:
NOTE For more detailed descriptions please seeOWL Web Ontology Language Guide - Definitions(http://www.w3.org/TR/2004/REC-owl-guide-20040210/#BasicDefinitions)
While OWL is similar in nature to other languages such as EXPRESS or UML, it has its own focus. Some of the concepts which modellers use in those languages are not available in OWL.
<owl:Class rdf:about="#HumanBeing"> <owl:equivalentClass> <owl:Class> <owl:unionOf rdf:parseType="Collection"> <owl:Class rdf:about="#MalePerson"/> <owl:Class rdf:about="#FemalePerson"/> </owl:unionOf> </owl:Class> </owl:equivalentClass> </owl:Class> <owl:Class rdf:about="#MalePerson"> <rdfs:subClassOf rdf:resource="#HumanBeing"/> <owl:disjointWith rdf:resource="#FemalePerson"/> </owl:Class> <owl:Class rdf:about="#FemalePerson"> <rdfs:subClassOf rdf:resource="#HumanBeing"/> <owl:disjointWith rdf:resource="#MalePerson"/> </owl:Class>
OWL Web Ontology Language Guide (http://www.w3.org/TR/owl-guide/)
OWL Web Ontology Language Reference Guide (http://www.w3.org/TR/owl-ref/)
OWL Web Ontology Language Overview (http://www.w3.org/TR/owl-features/)