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Re: LANG: UML as reference point (was: LANG: frame paradigm)

From: Guus Schreiber <schreiber@swi.psy.uva.nl>
Date: Thu, 28 Mar 2002 15:21:07 +0100
Message-ID: <3CA326D3.10C480A4@swi.psy.uva.nl>
To: Jim Hendler <hendler@cs.umd.edu>
CC: Frank van Harmelen <Frank.van.Harmelen@cs.vu.nl>, www-webont-wg@w3.org
Jim Hendler wrote:
> >- default values for attributes
> >   Not even in Full OWL
> 
> I think the term "default" is used differently here - in UML the
> defaults can be, essentially, monotonic, in the sense that it is a
> default that a female mammal lactates to feed its young (this is
> definitional, no exceptions in the natural world)  --  using the
> notion of default as "All of them have this value so it doesn't have
> to be specified on each"

I don't think that this is the UML semantics for default value. Well,
actually most UML books do not do a good job at defining it. The User
Guide of the three amigo's [1] gives the example of a class "Wall" with
an attribute "isLoadBearing" which has a default value "false" (clearly
not true for every wall). No further explanation is given of what may
constitute a default value. The OMG UML document [2] uses the term
"initial" instead of "default" (which seems to stem from a programming
view). 

Guus

[1] Booch, Rumbaugh & Jaconson. The Unified Modelling Language User
Guide. Addison Wesley, 1999.

[2] http://www.rational.com/media/uml/post.pdf

-- 
A. Th. Schreiber, SWI, University of Amsterdam, Roetersstraat 15
NL-1018 WB Amsterdam, The Netherlands, Tel: +31 20 525 6793 
Fax: +31 20 525 6896; E-mail: schreiber@swi.psy.uva.nl
WWW: http://www.swi.psy.uva.nl/usr/Schreiber/home.html
Received on Thursday, 28 March 2002 09:24:30 GMT

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