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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>

Dan,

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 
want?

-ChrisW

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 
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 17:37:13 GMT

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