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Re: LC reply drafted

From: Bijan Parsia <bparsia@cs.manchester.ac.uk>
Date: Tue, 12 May 2009 20:54:11 +0100
Message-Id: <D2B632AC-17A5-4BED-B6CC-9645933E810B@cs.manchester.ac.uk>
To: Sebastian Rudolph <rudolph@aifb.uni-karlsruhe.de>, W3C OWL Working Group <public-owl-wg@w3.org>
On 12 May 2009, at 20:41, Sebastian Rudolph wrote:

> Dear all,
>
> if I interpreted the intention of the below LC comment correctly,  
> Richard would like to see an explicit statement that classes just  
> represent sets of individuals

But that would be to say something false. OWL Classes most obviously  
do not "just" represent sets of individuals (as they can be mapped to  
distinct sets in different interpretations). If anything, OWL Classes  
are first order logic formulae with one free variable (and thus, when  
atomic, correspond to monadic predicates).

> and that the notion of a "concept" is something related but different.
> I tried to address this by adding two sentences to the Primer  
> document, see the diff at
>
> http://www.w3.org/2007/OWL/wiki/index.php?title=Primer&diff=23464&oldid=23440

""In modeling, classes are often used to denote the extension sets of  
concepts of human thinking, like ''person'' or ''woman''."""

But this is precisely wrong:
	http://en.wikipedia.org/wiki/Definition#Intension_and_extension

(reductio ad wikipedia :)). So please don't use the word "extension".

The commentator has a strange idea of what a concept is (and of class,  
and of set). I don't really want to import them into an already  
tangled terminological situation.

> Find the proposed draft response at:
>
> http://www.w3.org/2007/OWL/wiki/LC2_Responses/RHM1


In general, readers of the primer aren't going to know what "extension  
set" (er... generally known as the *extension*) is, so this wouldn't  
be clarificatory even if it were right.

Cheers,
Bijan.
Received on Tuesday, 12 May 2009 19:54:46 UTC

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