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Re: ISSUE 5.18 Unique Names Assumption Support in OWL

From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
Date: Thu, 24 Oct 2002 09:55:22 -0400 (EDT)
Message-Id: <20021024.095522.111945258.pfps@research.bell-labs.com>
To: connolly@w3.org
Cc: jos.deroo.jd@belgium.agfa.com, www-webont-wg@w3.org

From: Dan Connolly <connolly@w3.org>
Subject: Re: ISSUE 5.18 Unique Names Assumption Support in OWL
Date: 24 Oct 2002 08:44:51 -0500

> On Thu, 2002-10-24 at 06:59, Peter F. Patel-Schneider wrote:
> [...]
> > On looking at http://www.w3.org/2000/10/swap/log.n3 I realize that the
> > intended meanings of the resources in the log: namespace are inherently
> > broken.
> 
> No, they are as designed.

This does not prevent them from being inherently broken.

> Perhaps they're not what you would prefer nor what you
> would expect. That doesn't make them broken.

From http://www.w3.org/2000/10/swap/log.n3

> #   n3 definition of some logical terms

...

> log:equalTo a rdf:Property;
>     rdfs:comment
> """Equality in this sense is actually the same URI.
> Do not confuse with daml:EquivalentTo.
> A cwm built-in logical operator.
> """.
> 
> log:notEqualTo a rdf:Property;
>     rdfs:comment
> """Equality in this sense is actually the same URI.
> Do not confuse with daml:EquivalentTo.
> A cwm built-in logical operator.
> """.

The intended meanings here are *not* logical terms at all.


> >  For example, log:notEqualTo works on the identifier (URI
> > (reference)) of its arguments, something completely outside the bounds of
> > standard logic. 
> 
> Yes, that surprised me too.
> 
> > This brings up a serious problem with the descriptions of CWM.  Sean Palmer
> > states that CWM is, in some sense, a forward chaining first-order predicate
> > logic inference engine.   However, if CWM is a reasoner over some logic,
> > then the logic is a highly unusual intensional logic, and not any standard
> > first-order logic.
> 
> Not all descriptions of cwm have this problem.

But this description is, in some sense, the authoritative one.  The home
page for CWM points to it as a more up to date description of CWM than the
CWM home page.

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

Peter F. Patel-Schneider
Bell Labs Research
Received on Thursday, 24 October 2002 09:55:35 GMT

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