This section last edited on DateTime() is part of the ["SKOS/Reference"] wiki draft.
Section: Concept Schemes
This section defines the vocabulary and formal semantics for the notion of a SKOS Concept Scheme.
The notion of a SKOS Concept Scheme is defined informally in the SKOS Primer.
The SKOS Primer also defines recommended practice for using rdfs:isDefinedBy to state a relationship between a SKOS Conceptual Resource and the SKOS Concept Scheme in which it is defined.
skos:ConceptScheme has type Class.
skos:ConceptScheme and skos:Concept are Disjoint Classes.
The graph below is Consistent.
ex:bar rdf:type skos:ConceptScheme .
Except for the semantic condition stated above, the formal semantics of skos:ConceptScheme are undefined.
The choice to leave the formal semantics of skos:ConceptScheme undefined has been made to allow different design patterns to be explored for using SKOS in combination with more formal languages such as OWL, and for using SKOS with query languages such as SPARQL.
For example, interpreting skos:ConceptScheme as a sub-class of owl:Ontology would be consistent with the SKOS semantics. This would also be consistent with using owl:imports to make logical import statements between SKOS Concept Schemes.
Interpreting skos:ConceptScheme as a sub-class of the class of named RDF graphs would also be consistent with the SKOS semantics. This would also be consistent with using the name (URI) of a SKOS Concept Scheme in SPARQL queries as the name of an RDF graph, to establish, for example, the provenance of a semantic relationship between two SKOS Conceptual Resources.
However, this interpretation might not be appropriate if, for example, different named RDF graphs were used to express different "states" or "versions" of a SKOS Concept Scheme.
(@@TODO something about how expressing information about changes and versions in SKOS Concept Schemes is a research problem at the time of writing, and has been post-poned by the WG?)
Also, this interpretation might not be appropriate if a SKOS Concept Scheme were interpreted as having different "expressions", e.g. as an RDF graph and an HTML document (in which case separate URIs might be required for the SKOS Concept Scheme, the RDF graph and the HTML document).
(@@TODO something about why this is unresolved/postponed?)
@@TODO this section is missing skos:hasTopConcept
@@TODO say something about deprecation of skos:inScheme