RE: SUO: Set/Class Distinction
Hi Pat,
Yes, the intent was to distinguish sets from classes on an
extensional/intensional basis, so that sets could be ad hoc collections of
things while the term 'class' was reserved for natural kinds and other sets
whose members are bound together by a defining property or conjunction of
properties. However, it has turned out to be impossible to give a
nontrivial specification of these properties. For example, consider the
three things on my desk right now: a print-out, a glass of water, and the
computer. This is classic example of an ad hoc collection, and yet the
members have properties in common, e.g. being composed of matter, being in
approximately the same location, having the same person as their custodian,
etc.
Thanks,
Ian
> -----Original Message-----
> From: Patrick Cassidy [mailto:pcassidy@bellatlantic.net]
> Sent: Monday, September 17, 2001 2:00 PM
> To: Ian Niles
> Cc: Standard-Upper-Ontology (E-mail)
> Subject: Re: SUO: Set/Class Distinction
>
>
> Ian --
> I thought that one of the distinctions was that
> sets are necessarily defined extensionally, whereas
> a Class may have a membership criterion such that
> the same class may have different members at
> different times. Is this a misunderstanding of what
> the present definitions mean?
>
> Pat
>
> =====================
>
> Ian Niles wrote:
>
> > Hi All,
> >
> > A while back John Sowa recommended that we eliminate
> the concept of
> > 'Class' in the SUMO, because it is not clearly
> differentiated from 'Set' and
> > because it does not seem to have any utility beyond the
> concept of 'Set'.
> > If no one objects, I'll go ahead and replace all of the
> occurrences of
> > 'Class' in the SUMO with 'Set'.
> >
> > Thanks,
> > Ian
> >
> >
>
>
> --
> =============================================
> Patrick Cassidy
>
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>