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Re: proposal for last session of July face-to-face (new issues?)

From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
Date: Wed, 19 Jun 2002 11:03:56 -0400
To: connolly@w3.org
Cc: www-webont-wg@w3.org
Message-Id: <20020619110356W.pfps@research.bell-labs.com>

From: Dan Connolly <connolly@w3.org>
Subject: Re: proposal for last session of July face-to-face (new issues?)
Date: 19 Jun 2002 09:29:02 -0500

> On Wed, 2002-06-19 at 09:05, Peter F. Patel-Schneider wrote:
> [...]
> > These leave three portions of OWL unspecified:
> > 
> > M1 What is an OWL KB in triple form, and, more importantly, what
> >    collections of triples are not OWL KBs?
> 
> I expect all collections of triples are OWL KBs; that's
> the way I read the DAML+OIL Note. It looks like a
> new issue belongs on our issues list.

Well if all collections of triples are OWL KBs then there are some 
problems.

For example, what is the meaning of a malformed list, i.e., a list 
1/ where some list node does not have a rest,
2/ where some list node does not have a first,
3/ where some list node has two first,
4/ where some list node has two rests,
5/ that is circular, or
6/ that is infinite.

For example, what is the meaning of a malformed restriction, i.e., a
restriction 
1/ that is missing an onProperty element,
2/ that has none of the other parts of a restriction, or
3/ that has more than one of the other parts of a restriction.

These are a problem for the DAML+OIL way of expressing the model-theoretic
semantics of triple KBs, but there is a solution there because the DAML+OIL
model theory keys off the (syntactic) triples, not the (semantic) IEXT.

[...]

> > M3 What is the formal meaning of an OWL KB?
> 
> Whatever we specify it to be, no?

[...]

> > 	http://www-db.research.bell-labs.com/user/pfps/owl/translation.html
> 
> There's also my proposal to do a model theory straight from
> the triple abstract syntax:
> 
>   * layering (5.3,5.10): a same-syntax model theory
>   Dan Connolly (Thu, May 30 2002)
>   http://lists.w3.org/Archives/Public/www-webont-wg/2002May/0264.html

Your proposal is not a model theory from the triple syntax but is instead a
model theory from RDFS interpretations.  Your way of specifying semantics
for triple KBs is *much* harder than specifying semantics from the triple
syntax.  In particular, it cannot handle malformed lists and restrictions
in the way that they are handled in the DAML+OIL semantics. 

> Dan Connolly, W3C http://www.w3.org/People/Connolly/

Peter F. Patel-Schneider
Bell Labs Research
Received on Wednesday, 19 June 2002 11:04:08 GMT

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