Re: SUO: RE: SUO Comment #3
David,
The solution of creating not-class (or more commonly not-predicate) is a
common one for getting frame systems out of a jam of not having real
logical negation. It does introduce the mild problem of creating a
proliferation of not- prefixed terms paired with every defined term, but is
a more serious issue if the expressions which need to be modeled are more
complex than simply N-ary relations. That problem does not have an easy
solution.
I don't think your point was to minimize these problems since I know
you're already aware of them, but I thought it would be useful to point out
these issues for the group.
Adam
At 03:33 PM 8/15/2000 -0700, David Whitten wrote:
> >
> >
> > Dear Bill,
> >
> > See responses below.
> >
> > Regards
> > Matthew
> > ============================================
> > Matthew West
> > Asset Information Management
> > Shell Services International
> > H3229, Shell Centre, London, SE1 7NA, UK.
> > Tel: +44 207 934 4490 Fax: 7929
> > E-mail: Matthew.R.West@is.shell.com
> > http://www.shellservices.com/
> > ============================================
> >
> > > -----Original Message-----
> > > From: Bill Andersen [mailto:andersen@ontologyworks.com]
> > > Sent: 15 August 2000 19:50
> > > To: West, Matthew MR SSI-GPEA-UK
> > > Cc: Schoening, James R CECOM DCSC4I; Standard-Upper-Ontology (E-mail)
> > > Subject: Re: SUO Comment #3
> > >
> > >
> > > "West, Matthew MR SSI-GPEA-UK" wrote:
> > > >
> > > > Dear Bill,
> > > >
> > > > I don't think it is as bad as you make out.
> > > >
> > > > As far as I can see, conformance to the SUO means using the
> > > > terms of the SUO with the meaning of the formal definition
> > > > defined by the SUO in the SUO language.
> > >
> > > Right... But that might not (probably won't) be possible even in
> > > principle in the case of RDF, for example, which doesn't even admit
> > > negation. The compilation target system has to be capable of the
> > > semantic expressiveness of the SUO language. Perhaps there are W3C-
> > > like proposals for XML-based languages of this sort, but I'm not
> > > aware of them. We're talking pretty much full FOL for the SUO lang-
> > > uage and all of the XML-based languages being considered for popular
> > > use come nowhere close in expressiveness. That means approximation
> > > will be required. As Mike Uschold commented, he doesn't see this
> > > approximation as that much of a problem, but it's still a problem.
> > MW: Well there are two possibilities here, either you can only
> > partially map the SUO into the environment, and the implication
> > is that if negation can't be mapped, then it isn't relevant to
> > the purposes of that envirnonment, so is not missed. Or you
> > model negation in the environment. I'm not familiar with RDF,
> > but entity-relationship models have the same problem. However,
> > with the constructs of entities attributes and relationships,
> > I can create a model that will handle negation, so then it is
> > not a problem, only a matter of how to solve it.
>
>I'm not sure how Matthew is intending to create such a
>model, but one possibility of a 'compilation' that handles
>negation (imperfectly) would be to create a new class
>(call it not-class1). Assuming class1 is a partition of parclass,
>it is sufficient to define not-class1 as the union of all other
>subclasses of parclass.
>
>This does have the problem of determining what classes along
>with class1 provide a complete partition of its parent class,
>and may falter if you can't define negation of class1 as the
>'set difference' of class1 and its parent class.
>
>It also depends on a static class structure. so that non-class1
>may be defined properly.
>
>David Whitten
>
>PS. if someone sees an obvious flaw in my construction, I'd
>appreciate a note pointing out my error.
-----------------
Adam Pease
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