Re: Paper on Quantities in OWL

Dear Kendall and Bijan,

The paper is very interesting. I am just going on holiday for a few days
would like to make some detailed comments when I return.

An initial thought is that probably both an OWL-extension approach and an
ontology-based approach will exist side by side. The OWL-extension approach
has the benefit of easier computability.

However, the ontology based approach is also important, for two reasons:

1) There are circumstances in which it is necessary to identify a quantity
(e.g. 5.3 metres, the freezing point of gold - one of the calibration points
in ITS90), a quantity space (e.g. length, temperature, earthquake
magnitude), a unit (e.g. metre), or a scale (e.g. Celsius, Richter),  and to
make statements about it.

A statement about a quantity can be its numerical value according to a unit
or scale, but can also be more complicated than that.

2) W3C does not have the expertise to deal with all of quantities, units and
scales. Hence we need to engage the community which standardises in this
area. If we are going to ask them to assign URIs to these objects, then
there needs to be a precise definition of what the objects are and how they
relate to each other. So we have an ontology whether we like it or not.

For me the ideal solution would be an ontology for quantities, units and
scales, for which a special syntax is available. This would allow some users
to use the special syntax and ignore the ontology, and others to use the
ontology and ignore the special syntax.

Best regards,
David

At 16:27 19/08/2008 +0100, you wrote:
>
>Hi folks,
>
>As promised, I've a paper on handling quantities in OWL including unit
>conversion and dimensional analysis. Here's a link:
>      <http://clarkparsia.com/files/pdf/units-owled2008-eu.pdf>
>
>(BTW, David, I'm sorry I missed your poster for ISWC. The w3c was
>blacklisting me for a while ;))
>
>The key point is to build quantity support directly into OWL rather
>than to have an ontology based approach. I think the advantages in
>usability, clarity, and expressiveness are well worth the increased
>difficulty of extensibility. I'll be releasing the "preprocessing"
>version of the implementation in the near future so people will be
>able to play with it. We plan to add this to the OWL API and to Pellet
>directly.
>
>I'd very much love feedback about what base dimensions, base units,
>names should be supported. Other feedback, of course, welcome.
>
>--
>Cheers,
>Bijan.
>
>http://clarkparsia.com
>
>
>

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David Leal
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Received on Thursday, 21 August 2008 08:33:32 UTC