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RE: MT RDFS closure rule bug?

From: Jan Grant <Jan.Grant@bristol.ac.uk>
Date: Fri, 28 Jun 2002 10:40:48 +0100 (BST)
To: pat hayes <phayes@ai.uwf.edu>
cc: Dan Connolly <connolly@w3.org>, Jeremy Carroll <jjc@hplb.hpl.hp.com>, w3c-rdfcore-wg <w3c-rdfcore-wg@w3.org>
Message-ID: <Pine.GSO.4.44.0206281038270.28677-100000@mail.ilrt.bris.ac.uk>

On Fri, 28 Jun 2002, pat hayes wrote:

>
> >On Wed, 2002-06-26 at 04:08, Jeremy Carroll wrote:
> >[...]
> >>  Any interpretation of any
> >>
> >>  > >aaa [rdfs:range] yyy
> >>  > >yyy [rdfs:subClassOf] zzz
> >>
> >>
> >>  is an interpretation of
> >>
> >>  > >aaa [rdfs:range] zzz
> >
> >I don't think our specs say that.
> >
> >
> >>  thus the closure rule holds.
> >>
> >>  (Not) Proof:
> >>
> >>  Ahh, it depends on rdfs:range not being in the domain of discourse.
> >>  neglecting that little factette and invalidating the proof ...
> >>
> >>  Whenever
> >>  iii aaa jjj .
> >>  then
> >>  jjj [rdf:type] yyy .
> >>  hence
> >>  jjj [rdf:type] zzz .
> >>
> >>  hence
> >>
> >>  aaa [rdfs:range] zzz .
> >>
> >>  ==
> >
> >Where does that last step come from? Which part of our
> >spec allows you to conclude the rdfs:range triple?
>
> Right, exactly: it doesn't, and shouldn't. Jeremy: remember that a
> class isn't just its extension.

That's true, but is a subClassOf declaration just making a claim about
a subset relationship between extensions? If

	yyy [rdfs:subClassOf] zzz .

then every yyy _is_ a zzz (not just everything in the extension of yyy
is in the extension of zzz). If rdfs:subClassOf is pronounced
"rdfs:subSETOf" then we ought to consider fixing the spelling.

> Even if the range of aaa had exactly
> the same members as yyy, it still wouldn't follow that yyy *was* the
> range of aaa.
>
> Pat


-- 
jan grant, ILRT, University of Bristol. http://www.ilrt.bris.ac.uk/
Tel +44(0)117 9287088 Fax +44 (0)117 9287112 RFC822 jan.grant@bris.ac.uk
and Nostradamus never dreamed of the Church of the Accellerated Worm
Received on Friday, 28 June 2002 05:43:32 EDT

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