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Re: draft response for LC comment 31

From: Ivan Herman <ivan@w3.org>
Date: Sat, 14 Feb 2009 12:07:14 +0100
Message-ID: <4996A5E2.5010304@w3.org>
To: "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>
CC: public-owl-wg@w3.org

I am not 100% convinced by this answer, I think we should have some
discussion either on the call or the f2f. Reading through Frank's
comments, I do not find it unreasonable to have a dedicated annotation
property that indicates the level of ontology which is intended in spite
of all the caveats that you describe. Of course, tools have to be
careful not to believe this mark but it at least opens the door for some
reasonable conventions that the community could follow. The fact that
some of the datasets/ontologies might be enormous is a compelling
argument to have something like that around...

Yes, this could be one of those extra small things that lead to hell,
something you referred to at the last meeting. Nevertheless... I would
like to have some discussions on this, if possible.



Peter F. Patel-Schneider wrote:
> [Response for LC Comment 31]
> Dear Frank (and many others),
> Thank you for your message
>   http://lists.w3.org/Archives/Public/public-owl-comments/2009Jan/0038.html
> on the OWL 2 Web Ontology Language last call drafts, which the WG has
> taken to concern adding a syntactic marker for the expressive power of
> used in an ontology, including which profile the ontology belongs
>   within.
> One problem with having an expressive power marker in the header of an
> OWL ontology is that there are syntaxes for OWL ontologies, in
> particular the preferred syntax, RDF/XML, where the header information
> is mixed in with the rest of the ontology.  Recovering the ontology
> header in such syntaxes can thus require parsing the entire ontology.
> Note that simple text processing is not adequate as the marker syntax
> could occur in places where should not be interpreted as the marker,
> e.g., in comments or not attached to the ontology node.
> Another problem is how to treat cases where the expressive power of the
> ontology does not match the marker.  This is very different from what to
> do if an ontology does adequately reflect reality.  Should tools be
> required to reject ontologies where the expressive power of the ontology
> is greater than what the marker states?  Should tools be required to
> reject ontologies where the expressive power of the ontology is less
> than what the marker states?  Should nothing be said?  What guarantees
> should a search for expressive markers provide?  The answers to these
> questions are not obvious.
> The current situation leaves open the possibility that users will get
> together and, through practice, provide the answers to these thorny
> questions.  Ontology annotations can be used to support this effort.  If
> a body of practice arises, then it may be appropriate for a subsequent
> working group to consider adding this practice to OWL.
> Therefore the OWL WG does not intend to make any changes in response to
> your comment.
> The discussion of WG issue 111 (see
> http://www.w3.org/2007/OWL/tracker/issues/111) is not directly related
> to expressive power markers for OWL ontologies.  Instead it more touches
> on the situation where an ontology only uses the expressive power of OWL
> 2 DL, but is supposed to be interpreted as an OWL 2 Full document, i.e.,
> that it could not have a finite interpretation.  The WG noticed that in
> such cases it is always possible to add an
> OWL-2-Full-semantically-vacuous triple to the ontology that is not
> acceptable in OWL 2 DL, and decided that this would be the preferred way
> to disambiguate.  Some of the discussion of issue 111 did touch on
> markers for expressive power but the issue itself did not require a
> solution to this problem.
> Please acknowledge receipt of this email to
> <mailto:public-owl-comments@w3.org> (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 


Ivan Herman, W3C Semantic Web Activity Lead
Home: http://www.w3.org/People/Ivan/
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Received on Saturday, 14 February 2009 11:07:48 UTC

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