OWL 2 (Full)

Although any well-formed RDF graph is technically an OWL 2 ontology, in practice the term is usually used only for RDF graphs which make use of the OWL vocabulary. Ontologies which fall outside of OWL DL are sometimes called "OWL Full" to emphasize they are not in DL.

It is not possible to do sound and complete reasoning with unrestricted (OWL Full) ontologies, so in practice many users limit themselves to some subset of OWL. They may chose an ad hoc subset — whatever is implemented by the tools they use — but for interoperability, they are encouraged to use one of the standard subsets described here and defined in in OWL 2 Profiles.

OWL DL

@@@ description of OWL DL

OWL RL

OWL-RL is a subset of OWL for which forward-chaining rule engines can compute all entailments. For ontologies within this subset, an OWL-RL reasoner (based on such a rule engine) can find all answers and know that it has done so. It can also determine which entailments do not hold.

OWL-RL reasoners can be used with all OWL 2 ontologies (including OWL 2 Full), but for ontologies outside of RL, the reasoners may fail to find some entailments and will be unable to determine when they have found all entailments or whether something is a non-entailment.

The syntactic features allowed in OWL-RL are...

OWL QL

@@ description of QL

Intersection of OWL RL and OWL QL

The intersection of RL and QL is fairly small, .... @@@

OWL EL

@@ description of OWL-EL. ....

Intersection of OWL RL and OWL EL

@@ description of RE

Intersection of OWL QL and OWL EL

@@ description of QE

Intersection of OWL RL, OWL QL, and OWL EL

@@ description of RQE