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Re: Proposed Reply to Martin Merry -- New attempt

From: Dan Connolly <connolly@w3.org>
Date: 16 Jun 2003 11:50:39 -0500
To: Jim Hendler <hendler@cs.umd.edu>
Cc: webont <www-webont-wg@w3.org>
Message-Id: <1055782238.27167.173.camel@dirk.dm93.org>

This seems to be responsive to the comment[9May]
and consistent with WG proceedings; the WG
decided [15May] to drop "Complete OWL DL Consistency Checker"
and the remaining changes are editorial
and largely consistent with advice from the WG
to the editor.

Please do send it, Jim.


On Mon, 2003-06-16 at 09:48, Jim Hendler wrote:
> Dear Mr. Merry-
>  Thanks much for your comments.  They have caused us a lot of
> discussion and we have spent a lot of time working out how we could
> set the expectations better, as to the differences between OWL FUll
> and OWL DL. 
> First, we have dropped the discussion of a "Complete OWL DL
> Consistency Checker" from the Test document.  We believe this is
> consistent with your request 
> Second, in the overview we say
> "Owl Lite also has a lower formal complexity than OWL DL, see
> <reference section 8.3> for further details."
> Section 8.3 says:
> The idea behind the OWL Lite expressivity limitations is that they
> provide a minimal useful subset of language features, that are
> relatively straightforward for tool developers to support. The
> language constructs of OWL Lite provide the basics for subclass
> hierarchy construction: subclasses, value and cardinality
> restrictions. In addition, OWL Lite allows properties to be made
> optional or required (using the cardinality features). The limitations
> on OWL Lite place it in a lower complexity class than OWL DL. This can
> have a positive impact on the efficiency of complete reasoners for OWL
> Lite.
> Section 8.2 (On OWL DL) now reads
> These constraints of OWL DL may seem like an arbitrary set, but in
> fact they are not. The constraints are based on work in the area of
> reasoners for Description Logic, which require these restrictions to
> provide the ontology builder or user with reasoning support. In
> particular, the OWL DL restrictions allow the maximal subset of OWL
> Full against which current research can assure that a decidable
> reasoning procedure can exist for an OWL reasoner.
> We believe these changes help set the expectations more correctly as
> you requested.
> You also raised an issue as to whether we should remove features from
> the current OWL DL.  The issue you raised is that with both
> owl:inverseOf and owl:oneOf (and/or hasValue) in the language, the
> complexity class of OWL DL is higher.  This is true.  On the other
> hand, you state that
> At 3:18 PM +0100 5/9/03, Merry, Martin wrote:
> The theoretical results for the decidability of OWL DL are interesting
> but
> not particularly helpful. OWL Lite is justified by practical results
> in DL
> systems (primarily from Ian Horrocks). There is no such practical
> experience
> for the OWL DL subset.  We would like to see such practical experience
> before OWL exits candidate recommendation.
>  The WG has been made aware of implementations of OWL DL that include
> both inverseOf and oneOf and which seem to be performing well in
> practice.  The working group will definitely consider their status and
> usability before deciding on our schedule with respect to Candidate
> Recommendation and Proposed Recommendation.
> Thank you for your comments, please let us know if our response is
> acceptable and we can close this comment.
Dan Connolly, W3C http://www.w3.org/People/Connolly/
office: tel:+1-617-395-0241 (new VoIP phone Mar 2003)
mobile: tel:+1-816-616-6576
mobile: mailto:connolly+pager@w3.org
Received on Monday, 16 June 2003 12:50:12 UTC

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