- From: Stephen Reed <reed@cyc.com>
- Date: Thu, 15 Sep 2005 07:37:24 -0500 (CDT)
- To: Ian Horrocks <horrocks@cs.man.ac.uk>
- cc: Matt Williams <matthew.williams@cancer.org.uk>, <www-rdf-logic@w3.org>
Ian,
If I understand you correctly, a form of negation can be expressed in OWL
by creating an otherwise opaque class whose comment says "not exists
R.C", and asserting that the individual in question is an instance of this
class. If so, then what more can we say about the class so that a
reasoner could classify a novel individual with respect to presence of
R.C? Or what other interesting things could we assert in OWL about this
class.
I am robustifying Cyc's (a higher order knowledge base) OWL export tool
and am interested in minimizing the loss of expressiveness - in this case
negation.
Cheers.
-Steve
On Thu, 15 Sep 2005, Ian Horrocks wrote:
>
> On 12 Sep 2005, at 20:25, Matt Williams wrote:
>
> >
> > Dear List,
> >
> > Rather a basic question, and it may have been answered, but I couldn't
> > find anything in the archives.
> >
> > I'm wondering if I can say "not R.C" (where R and C are a role and
> > class
> > respectively). I'm trying to express a concept such as "doesn't have
> > treatment with tamoxifen", so I'm not really looking for the complement
> > of R, just a way of expressing that the relationship R.C won't hold for
> > a particular individual.
>
> It seems that what you mean is "not exists R.C". This is a perfectly
> good class/concept, and you can simply assert that the individual in
> question is an instance of this class.
>
> Ian
>
>
>
> >
> > Thanks a lot,
> >
> > Matt
> >
> >
> >
>
>
>
--
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Received on Thursday, 15 September 2005 12:38:54 UTC