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Re: OWL CR feedback: owl:Class 'vs' rdfs:Class causing pain. Is owl:Class really needed?

From: pat hayes <phayes@ihmc.us>
Date: Thu, 18 Sep 2003 18:34:16 -0500
Message-Id: <p06001f0dbb8fef84864b@[]>
To: Dan Connolly <connolly@w3.org>
Cc: Dan Brickley <danbri@w3.org>, www-rdf-comments@w3.org, public-webont-comments@w3.org

>Pat, this is perhaps a useful perspective on
>the matter, but what's at issue in this
>public-webont-comments forum is whether the
>question is answered by the OWL specs.

Well, OK. It is, but you have to kind of dig around to find it.

>Please try to answer the question from
>the text of the specs. If you guys just
>want to discuss this stuff free-form, please
>use www-rdf-logic or whatever.

Ok, the specs documents cover this issue at various places, eg see


See also the comments at
which gives a more formal description of the OWL-DL restrictions on 
the RDFS universe.


>On Wed, 2003-09-17 at 21:35, pat hayes wrote:
>>  [...]
>>  >Are all RDF classes OWL classes?
>>  No. RDFS has a more general notion of class than OWL has. In
>>  particular, rdfs:Class is not an OWL class.
>>  >and vice-versa?
>>  Yes.
>>  >Can this be expressed
>>  >with (rdfs):subClassOf?
>>  Yes, in RDFS:
>>  owl:Class rdfs:subClassOf rdfs:Class.
>>  However, this fact is 'invisible' in OWL because of the restrictions
>>  which have been placed on the expressivity of OWL syntax
>Dan Connolly, W3C http://www.w3.org/People/Connolly/

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Received on Thursday, 18 September 2003 19:34:17 UTC

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