Add OWL-SKOS mix-in class

This patch adds initial support for SKOS taxonomies as a
hierarchy-enabled alternative to UCO's current string-vocabularies
practice.

While the typical SKOS namespace is prefixed, the import of SKOS is
done by referencing an OWL-DL compatible subset of SKOS as a version IRI
import.  (See SKOS Reference C.3.)

Paul Brandt identified the SKOS strategy used in this patch, though his
initial draft was in another repository.  I ported the property to UCO's
ontology repository due to needing to satisfy references for SHACL.

This patch is a reduction from the first definition of
`core:TaxonomicConcept` drafted for UCO CP-99.

References:
* [OC-140] (CP-99) UCO should provide a SKOS taxonomy of device types
  for observable:deviceType
* #363
* https://www.w3.org/TR/skos-reference/#namespace-documents
  Section C.3, "SKOS RDF Schema - OWL 1 DL Sub-set (informative)"

Co-authored-by: Paul Brandt <[email protected]>
Signed-off-by: Alex Nelson <[email protected]>

ontology/core/core.ttl

@@ -1,15 +1,19 @@
+# imports: http://www.w3.org/TR/skos-reference/skos-owl1-dl.rdf
+
 @prefix core: <https://ontology.unifiedcyberontology.org/uco/core/> .
 @prefix owl: <http://www.w3.org/2002/07/owl#> .
 @prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
 @prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
 @prefix sh: <http://www.w3.org/ns/shacl#> .
+@prefix skos: <http://www.w3.org/2004/02/skos/core#> .
 @prefix types: <https://ontology.unifiedcyberontology.org/uco/types/> .
 @prefix xsd: <http://www.w3.org/2001/XMLSchema#> .
 
 <https://ontology.unifiedcyberontology.org/uco/core>
 	a owl:Ontology ;
 	rdfs:label "uco-core"@en ;
 	rdfs:comment "This ontology defines classes and properties that are shared across the various UCO ontologies.  At a high-level, the UCO core ontology provides base classes, relationship-oriented classes, content-aggregation classes, and shared classes."@en ;
+	owl:imports <http://www.w3.org/TR/skos-reference/skos-owl1-dl.rdf> ;
 	.
 
 core:Annotation
@@ -317,6 +321,13 @@ core:Relationship
 	sh:targetClass core:Relationship ;
 	.
 
+core:TaxonomicConcept
+	a owl:Class ;
+	rdfs:subClassOf skos:Concept ;
+	rdfs:label "TaxonomicConcept"@en ;
+	rdfs:comment "Taxonomic Concept is a mix-in class that enables UCO as an OWL ontology to use SKOS taxonomic individuals. [based on https://www.w3.org/2006/07/SWD/SKOS/skos-and-owl/master.html#Hybrids]"@en ;
+	.
+
 core:UcoObject
 	a
 		owl:Class ,

ontology/master/uco.ttl

@@ -1,3 +1,4 @@
+# imports: http://www.w3.org/TR/skos-reference/skos-owl1-dl.rdf
 # imports: https://ontology.unifiedcyberontology.org/uco/action
 # imports: https://ontology.unifiedcyberontology.org/uco/core
 # imports: https://ontology.unifiedcyberontology.org/uco/identity
@@ -24,6 +25,7 @@
 	a owl:Ontology ;
 	rdfs:label "uco-master"@en ;
 	owl:imports
+		<http://www.w3.org/TR/skos-reference/skos-owl1-dl.rdf> ,
 		<https://ontology.unifiedcyberontology.org/uco/action> ,
 		<https://ontology.unifiedcyberontology.org/uco/core> ,
 		<https://ontology.unifiedcyberontology.org/uco/identity> ,