LC Responses/MS4

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From PeterPatel-Schneider 12:49, 20 February 2009 (UTC) Added boilerplate at end

Dear Mike,

Thank you for your message 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
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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