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Re: proposals for the underlying principles of OWL

From: Dan Connolly <connolly@w3.org>
Date: 28 Aug 2002 12:09:06 -0500
To: "Peter F. "Patel-Schneider <pfps@research.bell-labs.com>
Cc: www-webont-wg@w3.org
Message-Id: <1030554546.23341.256.camel@dirk>

On Wed, 2002-08-28 at 11:38, Peter F. Patel-Schneider wrote:
[...]
> How the issues are resolved can only be completely determined by
> understanding the various documents.  However, the basics are as follows:

The progress on semantic layering looks interesting...

> Issue 5.3 Semantic Layering
> 	The semantic layering of OWL on top of RDFS is that OWL is a theory
> 	in an extension of RDFS.  In this theory, the OWL domain of
> 	discourse is not the entire RDF domain of discourse.


but the features of the language you're talking about are
very different from the features I'm interested in:

> 
> Issue 4.6 EquivalentTo
> 	EquivalentTo is removed from the language, as it is ill-typed.
> Issue 5.1 Uniform treatment of literal/data values	
> 	There is a strict separation between OWL object and data values.
> 	Removing the separation has computational consequences.

I'm not interested in a language like that.
The most important feature of the ontology layer, for me,
is daml:UnambiguousProperty, as specified by the axiomatization.
i.e. the ability to say "if X and Y have the same
state code, they're the same thing."

(for details, see these test materials:
  http://www.w3.org/2002/03owlt/sameStateP.rdf
  http://www.w3.org/2002/03owlt/sameStateC.rdf
)

I've seen suggestions that WebOnt should persue the description
logic features (tractable inference etc.) but some of the
useful looking features of DAML+OIL (UnambiguousProperty,
equivalentTo) should be added to RDFS. Those properties
were in earlier drafts of RDFS, after all; they were
left out because the WG wasn't clear on how to formalize
them. But now that we've got a formal understanding
of how RDFS works, it's no problem to add them.

I was thinking of this WG as the group to add those
features back on top of RDFS, but maybe that's not
what folks want to do.

-- 
Dan Connolly, W3C http://www.w3.org/People/Connolly/
Received on Wednesday, 28 August 2002 13:08:58 GMT

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