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Re: proposals for the underlying principles of OWL

From: Christopher Welty <welty@us.ibm.com>
Date: Wed, 28 Aug 2002 17:36:08 -0400
To: Dan Connolly <connolly@w3.org>
Cc: "Peter F. "Patel-Schneider <pfps@research.bell-labs.com>, www-webont-wg@w3.org, www-webont-wg-request@w3.org
Message-ID: <OFE5E238D9.74F13C4A-ON85256C23.00763659@pok.ibm.com>


You've lost me - I don't understand why you think dropping "equivalentTo" 
will prevent you from specifying unique mappings from "property" values to 
individuals, ie. a 1:1 mapping from a state code to a state. 

If, in your example, statecode is a "owl:property" that is both functional 
and inversefunctional, you will get this mapping.  Is that not what you 


Dr. Christopher A. Welty, Knowledge Structures Group
IBM Watson Research Center, 19 Skyline Dr.
Hawthorne, NY  10532     USA 
Voice: +1 914.784.7055,  IBM T/L: 863.7055
Fax: +1 914.784.6078, Email: welty@us.ibm.com

Dan Connolly <connolly@w3.org>
Sent by: www-webont-wg-request@w3.org
08/28/2002 01:09 PM

        To:     "Peter F.  "Patel-Schneider <pfps@research.bell-labs.com>
        cc:     www-webont-wg@w3.org
        Subject:        Re: proposals for the underlying principles of OWL


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 

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 
>                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 
> Issue 5.1 Uniform treatment of literal/data values 
>                There is a strict separation between OWL object and data 
>                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:

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 17:37:13 UTC

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