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Re: RDF as a syntax for OWL

From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
Date: Fri, 07 Jan 2005 10:32:11 -0500 (EST)
Message-Id: <20050107.103211.03194588.pfps@research.bell-labs.com>
To: geoff@sover.net
Cc: www-rdf-logic@w3.org

From: "Geoff Chappell" <geoff@sover.net>
Subject: RE: RDF as a syntax for OWL
Date: Thu, 6 Jan 2005 22:26:27 -0500

> 
> 
> > -----Original Message-----
> > From: www-rdf-logic-request@w3.org [mailto:www-rdf-logic-request@w3.org]
> > On Behalf Of Peter F. Patel-Schneider
> > Sent: Thursday, January 06, 2005 5:42 PM
> > To: geoff@sover.net
> > Cc: bparsia@isr.umd.edu; www-rdf-logic@w3.org
> > Subject: Re: RDF as a syntax for OWL
> > 
> > 
> > From: "Geoff Chappell" <geoff@sover.net>
> > Subject: RE: RDF as a syntax for OWL
> > Date: Thu, 6 Jan 2005 11:50:42 -0500
> > 
> > > > 3/ How will your code handle
> > > >
> > > > 	_:x rdf:type owl:Restriction .
> > > > 	ex:p1 rdf:type owl:ObjectProperty .
> > > > 	ex:c1 rdf:type owl:Class .
> > > > 	_:x owl:onProperty ex:p1 .
> > > > 	-:x owl:someValuesFrom ex:c1 .
> > > > 	_:x owl:allValuesFrom ex:c1 .
> > >
> [...]
> > 
> > > I suppose the right thing to do would be to flag the restriction as
> > > malformed? If so, I imagine rules along the lines of these could be
> > used:
> > 
> > Is it malformed?  This is part of the problem with using RDF as a syntax
> > carrier.
> 
> I guess I assumed that the point of the nnf exercise was extracting class
> descriptions in suitable form from a owl/rdf file to feed to a DL engine of
> some sort and so the usual DL-ish restrictions applied (e.g.:
> http://www.w3.org/TR/owl-ref/#Restrictions). In that case, yes, I would say
> it's malformed. I guess it's blurrier if it's owl full we're talking about.

Yes, the above would not be correct OWL DL, but in a fully RDF setting it
is not easy to so determine.

> BTW, are you aware of any formal statements about the semantic impact of
> malformed restrictions anywhere in the owl specs? I've seen some in drafts,
> but couldn't find anything in the current docs.

The OWL Full specs handle any RDF graph including unusual restrictions.
Just follow through the semantic definitions.

> I do recognize the difficulties involved here - there's no denying it's ugly
> to have to decree that certain triple patterns are disallowed or are
> required in your graph or you risk pockets of poorly defined meaning.

[...]

> > peter
> 
> Geoff

peter
Received on Friday, 7 January 2005 15:32:28 UTC

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