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[LC Response] To Jonathan Rees Re: Editorial comments on RDF-based semantics

From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
Date: Wed, 25 Mar 2009 14:34:55 -0400 (EDT)
Message-Id: <20090325.143455.38366472.pfps@research.bell-labs.com>
To: jar@creativecommons.org
Cc: public-owl-comments@w3.org
Dear Jonathan:
Thank you for your message
on the OWL 2 Web Ontology Language last call drafts.

Some of your comments in the message relate to specific editorial
concerns with the RDF-Based Semantics document.  These comments are
being addressed in another reply.  This response addresses only your
comments about the use of "OWL 2", "OWL 2 DL", and "OWL 2 Full".

The working group realizes that our documents did not do a good job of
describing the terminology related to OWL 2.  To alleviate this problem
there is now a new document, the Document Overview

The structure of OWL 2 ontologies is defined in the OWL 2 Structural
Specification and is not limited to ontologies that fit into a
Description Logic framework, but you are right in pointing out that this
was not made sufficiently clear.  The document has been revised so that
these features are described in their most general form using examples
in both structural and RDF graph forms. Restrictions required in OWL 2
DL ontologies are listed in Section 3, and it is made clear that these
only apply to OWL 2 DL ontologies.

The direct semantics directly provides one meaning for the constructs
in OWL 2 ontologies.  The RDF-based semantics directly provides a
meaning for all RDF graphs.  As all OWL 2 ontologies can be mapped into
RDF graphs, the RDF-based semantics provides another semantics for all
the constructs in OWL 2 ontologies.

The phrase "OWL 2", by itself, is now uniformly used to refer to the
entire language, regardless of the particular syntax or semantics.  The
phrase "OWL 2 Full", by itself, is now uniformly used as a shorthand to
refer to the treatment of RDF graphs (particularly those RDF graphs that
use OWL 2 constructs) under the RDF-based semantics and thus, as you
say, is a combination of both syntax and semantics.  This use of "OWL 2
Full" is consistent with the use of "OWL Full" in the WebOnt documents
that define the original version of OWL.

"OWL 2 DL ontologies" are then those OWL 2 ontologies that admit
reasoning using well-known DL techniques when interpreted using the
Direct Semantics, and that can be mapped to RDF graphs and back again
without affecting their meaning in the direct semantics.  This use of
"OWL 2 DL ontologies" is consistent with the use of "OWL DL" in the
WebOnt documents that define the original version of OWL."  Section 3 of
the OWL 2 Structural Specification provides a comprehensive and compact
list of the extra conditions that are required for an OWL 2 ontology to
be an OWL 2 DL ontology.

Several documents have had edits to conform to and better describe this
terminology.  In particular, the RDF-Based Semantics document, which was
not at last call, has been heavily edited.  The relevant edits have
ended up being interspersed with other work, so no diffs are provided
here.  The current working drafts of all the WG documents are linked to
from the WG home page.

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 Wednesday, 25 March 2009 18:33:33 UTC

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