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[LC Response] To Frank van Harmelen Re: Request for explicit URI's for language profiles

From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
Date: Thu, 19 Feb 2009 10:47:52 -0500 (EST)
Message-Id: <20090219.104752.46177907.pfps@research.bell-labs.com>
To: Frank.van.Harmelen@cs.vu.nl
Cc: public-owl-comments@w3.org
Dear Frank (and many others),

Thank you for your message
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.

As you point out, this kind of a marker was discussed in relation to WG
issue 111 (see http://www.w3.org/2007/OWL/tracker/issues/111).  We are
sorry that you find the discussion related to Issue 111 unconvincing -
after this discussion the WG decided that markers were in general not a
good idea.  In this message I have included some points related to
syntactic markers.

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.

In light of the discussion of Issue 111 and the reasons stated above the
OWL WG does not intend to make any changes in response to your comment.

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. 

Peter F. Patel-Schneider
on behalf of the W3C OWL Working Group 
Received on Thursday, 19 February 2009 15:48:04 UTC

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