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RE: [OEP] a Quantity pattern? [was: Re: [UNITS] FAQ : Constraints on data values range]

From: Uschold, Michael F <michael.f.uschold@boeing.com>
Date: Wed, 14 Apr 2004 17:16:44 -0700
Message-ID: <823043AB1B52784D97754D186877B6CF042668BA@xch-nw-12.nw.nos.boeing.com>
To: "Guus Schreiber" <schreiber@cs.vu.nl>, "Bernard Vatant" <bernard.vatant@mondeca.com>
Cc: "SWBPD" <public-swbp-wg@w3.org>

In cases where units and dimensions are important, then this may be a good guideline to work with. In most other cases, it may be extra baggage.  I worked with Gruber's physical quantities ontology and on the whole thought it to be very high quality, well thought out and w/ few if any errors.   


 -----Original Message-----
From: 	public-swbp-wg-request@w3.org [mailto:public-swbp-wg-request@w3.org]  On Behalf Of Guus Schreiber
Sent:	Wednesday, April 14, 2004 7:38 AM
To:	Bernard Vatant
Subject:	[OEP] a Quantity pattern? [was: Re: [UNITS] FAQ : Constraints on data values range]

Bernard Vatant wrote:
> I have not noticed any activity under [UNITS] so far ... this is a first bait :))
> A FAQ in Protégé-OWL list, I'll give here the latest variant sent yesterday (summed up)
> "I have defined a class 'Wheel'
> and a DatatypeProperty 'diameterValue'
> on Domain 'Wheel'
> and Range 'Integer'

Is this an opportunity for a modelling pattern?
Guideline: for numeric values, always use the "quantity" pattern
[Fowler, Gruber]

For example (in a sloppy fashion, other have done this better)
domain(Wheel) range(LengthQuantity))
domain(Quantity) range(Unit))
Retriction(unit, allValuesFrom(LengthQuantity))
type(Wheel) diameterValue(type(LengthQuantity) value(15) unit(cm)))
[the middle part is general and could come out of some units-and-dimensions ontology]
> I want to create a class 'BigWheel' with a restriction on the property
> 'diameterValue', for instance 'diameterValue => 10'.
> How do I do that in OWL?"
> I had answered that basically you can't express that kind of 'quantitative restriction' in
> OWL, although there are workarounds, like using a 'minDiameterValue' property and so on.
> I guess every other user wanting to include units in one's ontology will hit that kind of
> wall.
> It figures we should come out with clear explanations why OWL does not support
> quantitative restrictions on DatatypeProperty with numerical Range, and more generally
> restrictions linked to the very nature of data themselves, like defining the class
> 'WellDescribedThing' by restriction on a 'description' value to 'over 1000 words'.
> [Seems to me that there are many ways to work around declaration of those kinds of
> restrictions, but that OWL internally makes no provision to check their consistency, but
> can be used to pass them as black boxes to external applications that can make sense of
> them. IOW, I can declare an instance of 'BigWheel' with 'diameterValue' set to 9.7, no
> inconsistency will be detected by pure logical tools with 'minDiameterValue = 10', but
> external applications able to deal with quantities will make sense of it.]
> Bernard Vatant
> Senior Consultant
> Knowledge Engineering
> Mondeca - www.mondeca.com
> bernard.vatant@mondeca.com

Free University Amsterdam, Computer Science
De Boelelaan 1081a, 1081 HV Amsterdam, The Netherlands
Tel: +31 20 444 7739/7718
E-mail: schreiber@cs.vu.nl
Home page: http://www.cs.vu.nl/~guus/
Received on Wednesday, 14 April 2004 20:19:07 UTC

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