OWLRDF

OWLRDF is the RDF-based representation of the Web Ontology Language (OWL) used to encode OWL ontologies as RDF graphs. It is not a separate language but a mapping that translates OWL constructs into RDF triples so they can be stored, queried, and reasoned over in RDF tools.

In OWLRDF, ontologies use the standard OWL vocabulary (owl:Class, owl:ObjectProperty, owl:DatatypeProperty, owl:Ontology, owl:Restriction) along with RDF Schema predicates such as rdfs:subClassOf and rdfs:domain/range to express class hierarchies and property characteristics. Restrictions are represented with owl:Restriction nodes and properties such as owl:onProperty, owl:someValuesFrom, owl:allValuesFrom, and cardinality constraints.

An ontology encoded in OWLRDF can be serialized in RDF/XML or Turtle, making it interoperable with RDF triplestores and SPARQL processors. Reasoners and ontology editors that support RDF-based OWL can load OWLRDF representations to perform consistency checks, classification, and query answering.

Historically, OWLRDF describes how OWL semantics are encoded in RDF for OWL 1 and remains a basis for many tools, though OWL 2 has introduced additional serialization and semantics. In practice, modern OWL tools accept RDF serializations that use the OWL/RDF vocabulary and inferred triples may be generated by reasoning engines.

Limitations include potential verbosity and the need to understand blank node scoping, as well as the distinction between directly asserted triples and entailed inferences. OWLRDF remains a foundational representation for exchanging ontologies across RDF ecosystems.