4.1 Supported and Unsupported SKOS Semantics

This section describes features of SKOS semantics that are and are not supported by Oracle Database.

• Supported SKOS Semantics
  
• Unsupported SKOS Semantics
  

4.1.1 Supported SKOS Semantics

All terms defined in SKOS and SKOS extension for labels are recognized. When the SKOSCORE rulebase is chosen for inference, the recognized terms include the following:

skos:altLabel
skos:broader
skos:broaderTransitive
skos:broadMatch
skos:changeNote
skos:closeMatch
skos:Collection
skos:Concept
skos:ConceptScheme
skos:definition
skos:editorialNote
skos:exactMatch
skos:example
skos:hasTopConcept
skos:hiddenLabel
skos:historyNote
skos:inScheme
skos:mappingRelation
skos:member
skos:memberList
skos:narrower
skos:narrowerTransitive
skos:narrowMatch
skos:notation
skos:note
skos:OrderedCollection
skos:prefLabel
skos:related
skos:relatedMatch
skos:scopeNote
skos:semanticRelation
skos:topConceptOf
skosxl:altLabel
skosxl:hiddenLabel
skosxl:Label
skosxl:labelRelation
skosxl:literalForm
skosxl:prefLabel

Most SKOS axioms and definitions are supported including the following: S1-S8, S10-S11, S15-S26, S28-S31, S33-S36, S38-S45, S47-S50, and S53-S54. (See the SKOS detailed specification for definitions.)

Most SKOS integrity conditions are supported, including S9, S13, S27, S37, and S46.

S52 is partially supported.

S55, S56, and S57 are not supported by default.

• S55, the property chain (skosxl:prefLabel, skosxl:literalForm), is a subproperty of skos:prefLabel.

• S56, the property chain (skosxl:altLabel, skosxl:literalForm), is a subproperty of skos:altLabel.

• S57, the property chain (skosxl:hiddenLabel, skosxl:literalForm), is a subproperty of skos:hiddenLabel.chains.

However, S55, S56, and S57 can be implemented using the OWL 2 subproperty chain construct. For information about property chain handling, see Property Chain Handling.

4.1.2 Unsupported SKOS Semantics

The following features of SKOS semantics are not supported:

• S12 and S51: The rdfs:range of the relevant predicates is the class of RDF plain literals. There is no check that the object values of these predicates are indeed plain literals; however, applications can perform such a check.

• S14: A resource has no more than one value of skos:prefLabel per language tag. This integrity condition is even beyond OWL FULL semantics, and it is not enforced in the current release.

• S32: The rdfs:range of skos:member is the union of classes skos:Concept and skos:Collection. This integrity condition is not enforced.

• S55, S56, and S57 are not supported by default, but they can be implemented using the OWL 2 subproperty chain construct, as explained in Supported SKOS Semantics.