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Re: raised in comment: owl:class still needed? Does this effect Test LC?

From: Jeremy Carroll <jjc@hpl.hp.com>
Date: Mon, 26 May 2003 15:58:22 +0300
To: www-webont-wg@w3.org
Message-Id: <200305261558.22138.jjc@hpl.hp.com>

peter:
>The RDFS-compatible semantics for OWL DL heavily depends on owl:Class (more
>precisely, on IOC, the class extension of owl:Class).  If the distinction
>between owl:Class and rdfs:Class was removed the semantics would be quite
>different.

>I'm not even sure that an RDFS-compatible semantics for OWL DL, as distinct
>from an RDFS-compatible semantics for OWL full, would even be possible.  In
>particular, how could one arrange it so that the appropriate lists and
>descriptions existed?

It is clear that all references to owl:Class would need to be deleted, making 
the rdfs compatible semantics more dependent on IOC, which would remain a 
distinguished subset of rdfs:Class within OWL DL. The correspondence theorem 
would get harder :( 
There seem to be five references to :Class in S&AS rdfs compatible semantics.
Apart from the correspondence theorem the hardest text to rework would be the 
introductory text, because it is quite hard to articulate what rdfs:Class 
means.

[[
There are two different styles of using OWL. In the more free-wheeling style, 
called OWL Full, the three parts of the OWL universe are identified with 
their RDF counterparts, namely the class extensions of rdfs:Resource, 
rdfs:Class, and rdf:Property. In OWL Full, as in RDF, elements of the OWL 
universe can be both an individual and a class, or, in fact, even an 
individual, a class, and a property. In the more restrictive style, called 
OWL DL here, the three parts are different from their RDF counterparts and, 
moreover, pairwise disjoint.
]]

Possible additional sentence at end of extract

[[
In the <a link to section 4>syntax of OWL DL</a> rdfs:Class can
only be used to refer to only those  classes in IOC, hence rdfs:Class is
syntactically used as the name of IOC in both styles of OWL.
]]

 (IOC would need to be introduced earlier, currently where owl:Class is 
introduced)

In the OWL DL section further discussion of this would be necessary - the OWL 
DL section is quite difficult to change - I am still thinking what it would 
take.

Jeremy
Received on Monday, 26 May 2003 09:58:18 GMT

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