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Re: [ontac-forum] Neutrality Principle

To: ONTAC-WG General Discussion <ontac-forum@xxxxxxxxxxxxxx>
From: "John F. Sowa" <sowa@xxxxxxxxxxx>
Date: Sun, 27 Nov 2005 12:48:58 -0500
Message-id: <4389F18A.20204@xxxxxxxxxxx>
Dear Matthew,    (01)

In my recommendations for UF, I suggested that
it could be *huge*, but with very few axioms.    (02)

 > Are you aware just how small the UF really is?    (03)

I would expect it to include pump, but with very
little specification.    (04)

 > Take something like pump. In a 4D ontology this would
 > be represented by a set (unchanging membership) of
 > spatiotemporal extents. In a 3D ontology the members
 > are occupents. Now you could of course have a class
 > that was the superclass of these two, but you wouldn't
 > get a sensible answer from it for how many pumps there are.    (05)

And by the way, some people use the word "class" and some
use the word "type".  I prefer type because class is often
used as a synonym for "set", except when it isn't. In any
case, classes are typically defined extensionally, but the
types in an ontology should be definable even when there
aren't any examples (for example, when you're specifying
a design for a type of entity that hasn't yet been built).
In any case, the question of whether to use type or class
as a metalevel term should not have any influence on what
is included in the UF.    (06)

Comments:    (07)

  1. I would define a pump as "PhysicalObject", which would
     be a top-level undefined category.    (08)

  2. You could define PhysicalObject as a spatiotemporal extent,
     and Barry could define it as an occurrent.  Nothing in UF
     would refer to either spatiotemporal extents or occurrents.    (09)

  3. I would not expect *anybody* to use UF by itself for any
     kind of reasoning.  They would just import whatever they
     want and combine it with the more detailed axioms in
     whatever system they prefer.    (010)

John    (011)

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