LC Responses/JR7

From: Jonathan Rees <> Date: Sat, 31 Jan 2009 19:27:17 -0500 Message-Id: <> To:

The OWL 2 DL imports closure is subject to the prohibition on owl:incompatibleWith imports, while the OWL 2 Full imports closure is not.

It is unfortunate that there are two different definitions of imports closure. Ideally they should be instances of a common pattern, or one should be derived from the other. At least there should be some kind of theorem relating them, such as map-to-SS(import-closure(map-to- graph(O))) ~= import-closure(O) for all (DL) ontologies O, and the former is OK iff the latter is.

To answer the question in the editor's note in section 3 of the RDF- based semantics document: The answer is yes, this document does have to explain what imports mean, somehow, because imports is part of the OWL 2 vocabulary. Maybe your worry is that imports make a lie of the simple statement that every RDF graph has an OWL 2 Full semantics - i.e. graphs (or graph sets) that are not imports closed are not given a meaning. I don't know how to address this correctly but you're going to have to come to terms with this somehow - either retract the claim that all graphs have a meaning, say that the meaning is not RDF- semantics-like (because it relies on chasing imports), or say that unclosed graphs/ graph sets *do* have some meaning.

Best Jonathan

PeterPatel-Schneider 14:36, 13 February 2009 (UTC)

Dear Jonathan,

Thank you for your message

on the OWL 2 Web Ontology Language last call drafts.

The RDF Semantics document was not at last call. It has recently been changed so that imports is no longer a semantic issue. The editor of the RDF Semantics document will be working with you to improve the related presentation issues.

Please acknowledge receipt of this email to <> (replying to this email should suffice). In your acknowledgment please let us know whether or not you are satisfied with the working group's response to your comment.

Regards, Peter F. Patel-Schneider on behalf of the W3C OWL Working Group

Last modified on 24 February 2009, at 20:34