This might be a stupid question but it has been troubling me for quite some while. I know that OWL has three variants (Full, Lite and DL) and that the newer OWL2 has three profiles (EL, QL and RL).
Now my questions: - if a semantic reasoner supports OWL2, does that mean that is supports OWL Full too? - if a reasoner supports OWL2 EL, does it support OWL DL then or is it simply a reasoner that is only focussed on the OWL2 EL profile? - continuation of the above question, if it supports OWL2 EL, can such a reasoner be used to reason on normal ontologies?
Thx for your time
There is no reasoner that supports OWL 2 Full or OWL Full because they are undecidable - i.e., no reasoner can be complete on these languages. The OWL and OWL 2 profiles overlap to a point, but do not match exactly - OWL 2 DL includes a few more constructs than OWL DL, and there are features like keys which were not defined at all in OWL.
A reasoner that supports OWL 2 EL can be used on an ontology of any expressivity, but it will not return inferences that are only valid within OWL 2 DL - which means you'll still get correct answers, but they will be incomplete wrt the answers you would get from an OWL 2 DL capable reasoner. Reasoners that support a less expressive profile can be faster than reasoners that support a more expressive profile, since the underlying worst case complexity of reasoning is lower - i.e., for OWL 2 EL there are polynomial algorithms to compute inferences. That is not true for OWL 2 DL. This does not mean that any OWL 2 DL ontology will take more time to reason than any OWL 2 EL ontology, only that the simpler ontology is more predictable in terms of its requirements.