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Re: layering (5.3,5.10): a first-order same-syntax model theory

From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
Date: Thu, 20 Jun 2002 12:36:05 -0400
To: connolly@w3.org
Cc: www-webont-wg@w3.org
Message-Id: <20020620123605H.pfps@research.bell-labs.com>

From: Dan Connolly <connolly@w3.org>
Subject: Re: layering (5.3,5.10): a first-order same-syntax model theory
Date: 20 Jun 2002 10:55:17 -0500

> On Wed, 2002-06-19 at 17:21, Peter F. Patel-Schneider wrote:
> > Good.  A proposal.

[...]

> > 
> > And, of course, there are no comprehension constraints, so
> > 
> >      x rdf:type _:y .
> >      _:y one:intersectionOf1 a .
> >      _:y one:intersectionOf2 b .
> > 
> > does not entail that
> > 
> >      x rdf:type _:z .
> >      _:z one:intersectionOf1 b .
> >      _:z one:intersectionOf2 a .
> 
> Yes, that's by design. This is my position on...
> 
> http://www.w3.org/2001/sw/WebOnt/webont-issues.html#I5.10-DAML-OIL-semantics-is-too-weak
> 
> as I said earlier...
> 
> # DDTF/layering: weak class theory seems good enough (5.3, 5.10)
> Dan Connolly (Tue, May 28 2002)
> http://www.w3.org/2001/sw/WebOnt/webont-issues.html#I5.6-daml:imports-as-magic-syntax

If the decision is to have this sort of weak theory of descriptions, then
there are lots of options that are open.  However, some of them preclude
extensions to a strong theory of descriptions.  Even worse, some of them
preclude rational treatments of things like disjunction and negation.

On the other hand, if the decision is to have a strong theory of
descriptions, then comprehension principles are needed in your approach,
and comprehension principles are difficult to get right.


This, of course, brings up my point of quite some time ago that it would be
a good idea to get some of the basic behaviours of OWL ironed out.


peter
Received on Thursday, 20 June 2002 12:36:16 GMT

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