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[LC Response] To Michael Smith (was Re: The definition of entailment in the Direct Semantics document)

From: Michael Smith <msmith@clarkparsia.com>
Date: Tue, 24 Feb 2009 09:10:38 -0500
To: W3C OWL Working Group <public-owl-wg@w3.org>
Message-Id: <1235484638.6819.4.camel@31-35-250.wireless.csail.mit.edu>
Dear Mike,

Thank you for your message
http://lists.w3.org/Archives/Public/public-owl-wg/2009Jan/0031.html on
the OWL 2 Web Ontology Language last call drafts.

The OWL Direct Model-Theoretic Semantics [1] defines entailment in
terms of interpretations and requires that all URIs in an ontology are
present in the vocabulary of any interpretation satisfying that
ontology. The OWL 2 Direct Semantics [2] document defines entailment
in terms of models, a change which relaxes the vocabulary constraint.
The change is intentional -- it is useful because it permits
tautologies to be entailed by the empty ontology and simplifies the
semantic specification.

The difference is demonstrated by the test case you have cited [3].
This test is a positive entailment under the OWL 2 Direct Semantics,
but was a negative entailment under the OWL Direct Model-Theoretic
Semantics used when the WebOnt WG approved the test case.

The definition of entailment in the OWL 2 Direct Semantics document
will not be changed in response to your comment.

Please acknowledge receipt of this email to <mailto:public-owl- 
wg@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.
-- 
Mike Smith
on behalf of the W3C OWL Working Group

[1] http://www.w3.org/TR/owl-semantics/direct.html
[2] http://www.w3.org/2007/OWL/wiki/Direct_Semantics#Inference_Problems
[3] http://www.w3.org/2002/03owlt/Class/Manifest005#test
Received on Tuesday, 24 February 2009 14:11:51 GMT

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