4 Simple Knowledge Organization System (SKOS) Support

You can perform inferencing based on a core subset of the Simple Knowledge Organization System (SKOS) data model, which is especially useful for representing thesauri, classification schemes, taxonomies, and other types of controlled vocabulary.

SKOS is based on standard semantic web technologies including RDF and OWL, which makes it easy to define the formal semantics for those knowledge organization systems and to share the semantics across applications.

Support is provided for most, but not all, of the features of SKOS, the detailed specification of which is available at http://www.w3.org/TR/skos-reference/.

Around 40 SKOS-specific terms are included in the RDF Graph support, such as skos:broader, skos:relatedMatch, and skos:Concept. Over 100 SKOS axiomatic triples have been added, providing the basic coverage of SKOS semantics. However, support is not included for the integrity conditions described in the SKOS specification.

To perform SKOS-based inferencing, specify the system-defined SKOSCORE rulebase in the rulebases_in parameter in the call to the SEM_APIS.CREATE_INFERRED_GRAPH procedure, as in the following example:

EXECUTE sem_apis.create_inferred_graph('tstidx',sem_models('tst'), sem_rulebases('skoscore'), network_owner=>'RDFUSER', network_name=>'NET1');

Example 4-1 defines, in Turtle format, a simple electronics scheme and two relevant concepts, cameras and digital cameras. Its meaning is straightforward and its representation is in RDF. It can be managed by Oracle Database in the same way as other RDF and OWL data.

Example 4-1 SKOS Definition of an Electronics Scheme

ex1:electronicsScheme rdf:type skos:ConceptScheme;
 
ex1:cameras rdf:type skos:Concept;
   skos:prefLabel "cameras"@en;
   skos:inScheme ex1:electronicsScheme.
 
ex1:digitalCameras rdf:type skos:Concept;
   skos:prefLabel "digital cameras"@en;
   skos:inScheme ex1:electronicsScheme.
 
ex1:digitalCameras skos:broader ex1:cameras.

• Supported and Unsupported SKOS Semantics
  This section describes features of SKOS semantics that are and are not supported by Oracle Database.
• Performing Inference on SKOS RDF Graphs
  Performing inference on a SKOS RDF graph is similar to performing inference on an RDF graph.