LC Responses/FH2

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To: Frank van Harmelen <Frank.van.Harmelen@cs.vu.nl>
CC: public-owl-comments@w3.org
Subject: [LC response] To Frank van Harmelen

Dear Frank,

Thank you for your comment
     <http://lists.w3.org/Archives/Public/public-owl-comments/2009Jan/0035.html>
on the OWL 2 Web Ontology Language last call drafts.

OWL 2 is a successor of OWL and not only a successor of OWL DL. You are right, however, in pointing out that this is not made sufficiently clear in some documents, and that they sometimes seem to suggest that this is not the case.

In order to address this problem the WG has added a Document Overview and has revised several of the other documents. The Document Overview provides a high level view of the design, making it clear that OWL 2 refers to the language as a whole, that an OWL 2 ontology can be equivalently seen as an RDF graph or as an abstract structure (an instance of the ontology class), and that ontologies can be interpreted using either the RDF-Based semantics or the Direct semantics.

The Structural Specification and Functional-Style Syntax document was always intended as a specification of the features provided by OWL 2 as a whole, 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. Finally, where syntactic/structural restrictions are mentioned in the remainder of the document it is similarly made clear if they only apply to the DL case.

An audit of the remaining documents has also been carried out in order to ensure that they follow the same principles, and in particular that the unqualified use of OWL 2 is always a reference to the language as a whole.

We hope that these changes address your concerns.

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.

Regards,
Ian Horrocks
on behalf of the W3C OWL Working Group



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Many documents seem to suggest that the term "OWL2" is only applied to

the OWL2 DL fragment. For example, the "Direct Semantics" document says:

> This document provides the direct model-theoretic semantics for OWL 2

and

> Since OWL 2 is an extension of OWL DL ....

But in common usage, as well as in the OWL1 REC documents, the term "OWL" stands for the entire set of 3 sublanguages. E.g.

> OWL has three increasingly-expressive sublanguages: OWL Lite, OWL DL,
> and OWL Full.

(OWL1 Overview).

The term OWL2 suggests that it is a successor of OWL, whereas in fact it is only a successor of OWL DL.

Hence, we strongly insist that the names are adjusted to be in line with common practice. Thus, we would have OWL2 DL, OWL2 Full, OWL2 RL, and also OWL2 Full.

Notice that the conformance document <http://www.w3.org/TR/owl2-test/> properly speaks about OWL2 DL, OWL2 Full etc. We are asking for this to be done consistently across the entire document set, to avoid widespread confusion.