RE: viewpoints and multiple inheritance.
Dear Chris,
From what you say we ought to be in agreement, but it seems a rather violent
agreement at present.
See comments below marked MW:
Regards
Matthew
============================================
Matthew West
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============================================
> -----Original Message-----
> From: Christopher A. Welty [mailto:weltyc@cs.vassar.edu]
> Sent: 21 June 2000 17:54
> To: standard-upper-ontology@ieee.org
> Subject: RE: viewpoints and multiple inheritance.
>
>
>
>
> Dear Matthew,
>
> At 10:05 AM +0200 6/21/00, West, Matthew MR SSI-GPEA-UK wrote:
> >Dear Chris,
> >
> >Multiple inheritance (worked out bottom up rather than top
> down) is a matter
> >of the discovery of common factors with a certain structure.
>
> No, it isn't. This is precisely the kind of confusion that (perhaps)
> derives from the Object-Oriented "code-sharing" paradigm (to
> paraphrase John Thompson in this list) that I would like to avoid.
MW: I have never been concerned with code sharing, so I don't understand
this criticism. Let me try to explain what I really meant.
MW: An object may be a member of more than one class. If being a member of
the same set of classes happens often enough, we may wish to recognise the
intersection of these classes as being significant to us as a class.
Equally, we may start with a complex class, and over time recognise that it
is the intersection of a number of other classes, and define it as such.
Each class comes with a set of common properties that all its members have.
Since the objects that are members of the intersection class are also
members of all the superclasses, they will have the properties that are
common to all the superclasses. If this is not so, you have simply done
something wrong, and you need to look at your analysis more carefully, since
I am only restating some basic pieces of set theory here.
>
> Perhaps these factors can lead one to consider arranging properties
> in a taxonomy, but once you do it you have a universal assertion, not
> a sharing of factors. Regardless of whatever they have in common, if
> you say cat is-a pet then it means ALL cats are pets. THAT is what
> it means, and nothing else. Single or multiple, it doesn't matter.
MW: I agree.
>
> -Chris
>
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