- From: Sean Bechhofer <sean.bechhofer@manchester.ac.uk>
- Date: Wed, 30 Jul 2008 15:59:09 +0100
- To: public-webont-comments@w3.org
- Cc: SWD Working SWD <public-swd-wg@w3.org>
Dear OWL WG members, The SKOS vocabulary is intended for the representation of simple knowledge organisation schemes such as thesauri, term lists and controlled vocabularies. SKOS is designed to fit into existing Semantic Web standards, and to achieve this, an RDF Schema which defines the SKOS vocabulary has been produced. The development of this schema has highlighted issues relating to OWL species which are relevant to current work on OWL 2. In particular, the current schema is in OWL Full. It would be desirable if the SKOS vocabulary could be represented in OWL DL (or the equivalent of OWL DL in the OWL 2 space). Concepts in a SKOS vocabulary are defined as instances of the owl:Class skos:Concept. They may be related to other skos:Concepts using object properties such as skos:broader, skos:narrower and skos:related -- known as SKOS semantic relations. SKOS also provides a set of lexical labelling properties, such as skos:prefLabel and skos:altLabel. These are datatype properties, with RDF plain literals as values. Documentation properties including skos:note, skos:changeNote, skos:definition are also provided, allowing the decoration of concepts with additional information. In some circumstances, the expected value of a documentation property is a literal value (e.g. a simple textual note). In other circumstances, the value may be an object, for example the value of skos:changeNote may be a structured object containing information about a change along with provenance or date information. Documentation properties are defined as subproperties of skos:note. An additional use case for SKOS is as an annotation vocabulary for OWL ontologies. For example the SKOS vocabulary itself uses skos:changeNote and skos:definition to attach provenance and documentation information to the SKOS vocabulary terms. This then pushes the ontology out of OWL DL as object properties are being applied to classes. We envisage that SKOS properties will also be used to attach lexical information to OWL ontologies (for example, providing alternate names or labels for classes). Again, with the current situation, this results in OWL Full ontologies. One solution to this would be the provision of rich annotations. The SKOS documentation properties are essentially annotations and would ideally be represented as such, but with the addition of subproperty relationships between the properties (i.e, skos:note as a superproperty). The lexical labelling properties could also be considered as annotation properties. SKOS is intended to be extensible, however, so again allowing the possibility of providing subproperties of the lexical labelling properties is desirable. Support for punning, both in terms of class/instance and data/object property would also provide solutions to some of these issues. Rich annotations would, however, be our preference. Cheers, Sean -- Sean Bechhofer School of Computer Science University of Manchester sean.bechhofer@manchester.ac.uk http://www.cs.manchester.ac.uk/people/bechhofer
Received on Wednesday, 30 July 2008 14:59:20 UTC