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Re: [ontology-summit] URIs for quantities, units and scales

To: Ontology Summit 2009 <ontology-summit@xxxxxxxxxxxxxxxx>
From: "John F. Sowa" <sowa@xxxxxxxxxxx>
Date: Fri, 20 Mar 2009 15:52:29 -0400
Message-id: <49C3F3FD.1000502@xxxxxxxxxxx>
Dear Matthew,    (01)

Yes, I certainly agree about that:    (02)

MW> The homework has been done on units and measures. Engineers
 > and physicists are quite clear about what they mean for their
 > purposes whether or not they have defined that meaning in a
 > formal ontology, so for their purposes common identifiers and
 > looking them up in a standard when necessary works.    (03)

Excellent standards and agreements on the basic units were
established in the 19th century, and every decade or so,
an extra decimal digit is added.    (04)

C. S. Peirce, whom I have quoted many times, spent 30 years
working for the U. S. Coast and Geodetic Survey.  During that
time, he went around the world doing the best measurements of
gravity in the late 19th century.    (05)

Among his other accomplishments, Peirce was the first person to
recommend a wavelength of light as the basis for defining the
metre.  Furthermore, he actually designed and built the equipment
for using a wavelength of light to measure the lengths of the
pendulums he used for measuring gravity.    (06)

Doing that kind of work is the foundation for measurement, and
establishing unique identifiers is just one part of the problem.
As I said in my previous note, URIs can be a useful adjunct to
the well-established systems, but they're no better than the
garbage or gold at the other end of the pointer.    (07)

John    (08)


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