Dear Ed, (01)
> (3) Matt doesn't mention the CDIF notation for "subtype"/subsumption.
> This is a foundational concept in OWL, and it is very important to
> modeling measurement concepts. In particular, every 'measurement unit'
> is_a 'quantity'. I would be wary of a notation like:
> measurement-unit -- is a --> quantity (02)
[MW] I do not recall that CDIF has a specific notation, so you can either do
what you have done here, or quite often I use the EXPRESS notation as an
extension. (03)
> because it makes the notation ambiguous. 'is_a' is a class-to-class
> relationship, rather than an instance-to-instance relationship (like
> 'part of'). It models an axiom, not just a relation. That is:
> A -- is part of --> B
> models a relation "is part of" whose domain is things that satisfy
> relation (class) A, and whose range is things that satisfy relation B -
> -
> a vocabulary item. It has two free variables. Whereas,
> A -- is a --> B
> models a proposition, a statement: Every A is a B. Formally,
> (forall x) (if (A x) (B x))
> It has no free variables. And the model asserts that proposition,
> making it an axiom.
> So I would object to overuse of the arrow notation, if it leads to such
> an ambiguity. (04)
[MW] I'd just like to push back on this a bit. I agree that you need to be
careful to distinguish between relationships between classes and
relationships that hold between members of classes. However, I had
understood subtype/supertype as being able to be seen in either way. So that
one way of seeing subtype/supertype is as an identity relationship between
members of the subtype and members of the supertype. (05)
Comments?
>
> And finally, I did say that we need a language-selection committee. I
> didn't volunteer to lead it, precisely because we need some persons
> with
> more knowledge of the ontological Tower of Babel. We seem to have
> volunteers in the persons of Messrs. West, Bennett, and Walker. ;-) (06)
[MW] I had hoped that in suggesting something I had invalidated myself for
this role, since I can argue I have a vested interest. However, I have no
special objection to serving in this capacity, I have no special knowledge
of languages except as a user - as someone who has developed ontologies -
and I hope therefore has some idea of what the requirements on a language
should be. On the other hand, I would particularly welcome someone who knows
the ins and outs of languages like David Price being on the committee (sorry
David for landing you in it). (07)
Regards (08)
Matthew West
Information Junction
Tel: +44 560 302 3685
Mobile: +44 750 3385279
matthew.west@xxxxxxxxxxxxxxxxxxxxxxxxx
http://www.informationjunction.co.uk/
http://www.matthew-west.org.uk/ (09)
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>
> -Ed
>
>
> --
> Edward J. Barkmeyer Email: edbark@xxxxxxxx
> National Institute of Standards & Technology
> Manufacturing Systems Integration Division
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