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Re: XML Schema datatypes

From: Carsten Lutz <clu@tcs.inf.tu-dresden.de>
Date: Thu, 15 Nov 2007 09:12:51 +0100 (CET)
To: Bijan Parsia <bparsia@cs.man.ac.uk>
Cc: "Web Ontology Language (OWL) Working Group WG" <public-owl-wg@w3.org>
Message-id: <Pine.LNX.4.64.0711150906580.24037@frege.inf.tu-dresden.de>

On Thu, 15 Nov 2007, Carsten Lutz wrote:
>> Boundedness is an issue, but you can get that with integers and min and 
>> max. Which we have.
>
> If a user explicitly uses min and max in his modelling, he obviously
> believes that the boundedness is crucial for the modelling. Then, he
> should expect to have consequences that derive from that boundedness.
> I cannot see that this is in any contradiction to what I have advocated.
>
>> I don't see that as a fix. And if the issue is merely boundedness then we'd 
>> have to chuck user defined datatypes on the integers.
>
> I disagree.

After some fresh air on my way to work, let me add something. I should
maybe not have talked so much about "boundedness" in my previous mail,
but rather about machine datatypes vs mathematical datatypes. What I 
mean is:

- if somebody wants to represent months as an integer, it is very
   natural to use the bounded datatype {1,...,12}, which is easily
   defined from the mathematical datatype integer in terms of min and
   max. Of course, this should be supported and exploited in reasoning.

- with the machine datatypes from XML schema, there is a *particular
   reason* for the boundedness: data representation. And this is what
   I have asked a concrete example for: an inference where machine
   datatypes are exploited, i.e., where boundedness due to data
   representation plays a crucial role.

Maybe you are right that reasoning about database schemas is an
application where such examples can be found. Fine with me. Still, I
keep up my opinion that for an ontology language such as OWL, the
mathematical datatypes are the standard case, whereas the machine
datatypes are exceptional. Note also that many machine datatypes can
be represented in terms of mathematical datatypes when really needed
(e.g. in terms of min and max).

greetings,
 		Carsten


--
*      Carsten Lutz, Institut f"ur Theoretische Informatik, TU Dresden       *
*     Office phone:++49 351 46339171   mailto:lutz@tcs.inf.tu-dresden.de     *
Received on Thursday, 15 November 2007 08:13:08 GMT

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