- From: Jeremy Carroll <jjc@hpl.hp.com>
- Date: Wed, 16 Jan 2008 15:08:59 +0000
- To: Bijan Parsia <bparsia@cs.man.ac.uk>
- CC: OWL Working Group WG <public-owl-wg@w3.org>
Hi following points came up in HP internal discussion: a) there's currently no conformance requirement to implement entailment for OWL systems, and we would not expect such a requirement to be introduced. Jena implements entailment principally for passsing W3C entailment tests, rather than for end user functionality. The Jena implementation is fairly similar to the RIF implementation: on the LHS of an entailment a bnode is effectively skolemized, on the RHS a bnode becomes a variable in a SPARQL query. b) Bijan's proposal seems problematic for OWL Full, because bnodes corresponding to individuals get treated differently from structural bnodes (for example those introduced as part of an intersectionOf construct, with its rdf:List ...) c) strong support that Skolemization is a legitimate OWL implementation technique, and suggestion that the OWL WG should review the specs shortly before last call to ensure that nothing is said that furthers the misreading that Skolemization is not permitted. Some text explicit permitting Skolemizing implementations may be advisable. ==== in summary, not in favour of Skolemized semantics; but in favour of Skolemizing implementations. Jeremy
Received on Wednesday, 16 January 2008 15:09:21 UTC