Dear Steve, (01)
I suggest that creating a self-consistent ontology will take time, but
assigning URIs to quantities, units and scales will bring an immediate
benefit. The URIs can be used without an ontology within existing data models. (02)
Assigning URIs will start the two communities working together, and success
will provide the encouragement to work on the ontologies. The task will also
lead to a definition of the scope, which is not trivial - e.g. are we
concerned with ITS90? (03)
It is possible that there is not a single self-consistent ontology, but a
number of layers of ontology. The phyicists working on metrology may not
wish to go beyond the statements that:
- the lengths are an ordered set;
- the metre is a length, (04)
or in N3 (statements A):
iso80000:Length a maths:OrderedSet .
si:metre a iso80000:Length . (05)
Engineers working in CAD or GIS may wish to add (statement B):
iso80000:Length a maths:VectorSpace_1d .
because this is a valid assumption at scales relevant to CAD and GIS. (06)
Hence we might find statements A in an ontology created by ISO TC12 or BIPM,
which has a very high level of trust. Statement B would be contained in an
ontology publised by ISO TC211 or ISO TC184 and would still have a high
level of trust, but the trust would limited to the areas in which the
technical committees have responsibility. (07)
Best regards,
David (08)
At 07:27 20/03/2009 -0700, you wrote:
>David,
>Very interesting document. I have a question. Shouldn't a self-consistent
>ontology be created for units and quantities before the URIs are created?
>And would the creation of such an ontology be a good target for this
>community (arm in arm with TC12 and others)?
>
>- Steve
>
>-----Original Message-----
>From: David Leal [mailto:david.leal@xxxxxxxxxxxxxxxxxxx]
>Sent: Friday, March 20, 2009 2:33 AM
>To: steve@xxxxxxxxxxx
>Cc: jjb5@xxxxxxxxxxx; Howard.Mason@xxxxxxxxxxxxxx; Radack@xxxxxxx;
>dr.matthew.west@xxxxxxxxx; nicolas.figay@xxxxxxxx; david.price@xxxxxxxxxxxx;
>michel.bohms@xxxxxx
>Subject: URIs for quantities, units and scales
>
>Dear Steve,
>
>The attached document attempts to explain the need for URIs for quantities
>units and scales to the standardisation community. The document results from
>work within ISO TC184/SC4 and within the W3C Product Modelling XG, which
>identified the handling of units of measure on the Web as a key priority.
>
>There has been initial contact with Anders Thor the chair of ISO TC12, and
>with ISO CS, but it is difficult to make further progress because it
>impinges upon so many aspects of standardisation.
>
>The document has consensus as a summary, but David Price points out that
>dereferencing URIs for quantities, units and scales is a secondary issue,
>and that mentioning it may "frighten the horses".
>
>Best regards,
>David
>
>
>
> (09)
============================================================
David Leal
CAESAR Systems Limited
registered office: 29 Somertrees Avenue, Lee, London SE12 0BS
registered in England no. 2422371
tel: +44 (0)20 8857 1095
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e-mail: david.leal@xxxxxxxxxxxxxxxxxxx
web site: http://www.caesarsystems.co.uk
============================================================ (010)
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