Dear Joe, (01)
What I am saying is simpler than that. (02)
If we interpret the magnitude of length expressed as "30 m" as an
equivalence class of point pairs, then the statement: (03)
my_pair has_a_separation_of 30m (04)
is merely a statement of classification. (05)
The statement: (06)
my_ship has_a_waterline_length_of 30m (07)
is not a statement of classification. (08)
The relationship between my_ship and 30m is "indirect". It relies upon:
- relationship between my_ship and the two points at the intersection of the
waterline plane, the plane of symmetry, and the outside of the ship;
- the classification of that point pair as a member of 30m. (09)
Either statement can result more or less directly from a measurement process. (010)
Best regards,
David (011)
At 10:29 02/10/2009 -0400, you wrote:
>I am afraid that I'm not quite clear on the definition of "direct" and
>"indirect" with respect to quantities. Re-definition in terms of
"manifestation"
>and "dispositional" don't help me much.
>
>Perhaps if I try to parrot back what has been discussed in my own terms,
you can
>tell me whether or not I've got it.
>
>
>A direct quantity is an estimate of an attribute of a physical object
determined
>by an actual measurement event.
>
>An indirect quantity is a hypothetical estimate of an attribute of a physical
>object, not referring to an actual measurement event, but to the
possibility of
>such an event.
>
>
>jbc
>--
>_______________________________
>Joseph B. Collins, Ph.D.
>Code 5583, Adv. Info. Tech.
>Naval Research Laboratory
>Washington, DC 20375
>(202) 404-7041
>(202) 767-1122 (fax)
>B34, R221C
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> (012)
============================================================
David Leal
CAESAR Systems Limited
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