Frank,
Yes, F=ma is only a *theory* of motion, and as
I have mentioned in this thread, incompatible theories would have to be
maintained in some extension(s) to the basic FO. Sets of concepts that
are mutually dependent on each other for their description would have to be
located together – whether in the base FO or in some extension to
it. I was pleased that Matthew brought up the case of mathematically
described concepts, and this issue applies to many “derived” units
of measure such as acceleration. But in some cases that may appear to be
co-dependent, one of the elements such a “force” may also
correspond to a more basic concept, and be properly in the base FO as a true
primitive. Force can be directly perceived by the sense of touch, and
things that make direct sensory impressions have, in my view, a privileged status
as prime candidates for primitiveness. The physical equations relating to
force are not restricted to its effect on acceleration, but also include things
like the compression of a spring, and the intensity of pressure due to force on
a compressible fluid. So I think that “Force” would be a true
primitive, though “F=ma” would have to be in a ‘theories of
motion’ extension, along with Einstein’s equations. Although
the unit of force is a “derived” unit in the SI system, the effect of
force can be directly perceived, and this is a good reason (I think) to
consider it a primitive. “force” is also one of the words in the
Longman defining vocabulary.
The exact inventory of physical units of measure
that should be in the basic FO would have to be decided by the consortium
constructing it. I have not gone through the list to determine whether
all of the current SI units (meter, kilogram, second, ampere, kelvin, mole,
candela) are the only units that belong in the base FO. The coulomb, for
example, used to be considered as one of the base units (of electrical charge),
but is now considered as a derived unit (one amp-second). I would want
the coulomb to be in the base FO, but there may be arguments against that. If
they are considered non-controversial, I would hope that the consortium decides
to include derived units as well, for convenience. Perhaps if all the
non-controversial derived units were maintained in one extension, it would be almost
as convenient.
I think that a principle for construction of
the FO should be to include everything that is desired by someone, as long as
it is logically consistent with the rest. If it is clearly a derived
concept (not primitive as defined by the consortium), and is clearly relevant
to some restricted domain, then the consortium *may or may not* decide
to move it to that domain extension, even over the objections of some
contributors. This reflects the practical need to resolve disputes
quickly. The issue of what is or is not a primitive may have to be
resolved by majority vote in some cases.
Pat
Patrick Cassidy
MICRA, Inc.
908-561-3416
cell: 908-565-4053
cassidy@xxxxxxxxx
From:
ontolog-forum-bounces@xxxxxxxxxxxxxxxx
[mailto:ontolog-forum-bounces@xxxxxxxxxxxxxxxx] On Behalf Of Olken,
Frank
Sent: Monday, January 12, 2009 11:08 AM
To: [ontolog-forum]
Subject: Re: [ontolog-forum] FW: Next steps in using ontologies as
standards
Pat Hayes and Pat Cassidy,
These statements are only true for "Newtonian" conceptualizations
of time.
Relativistic models of "space-time" require the
specification of both spatial and
temporal locations. Relativistic temporal models arise in
astronomy, astrophysics,
high energy physics.
In a purely computer science context see the classic paper by
Leslie Lamport
on Time, Clocks, and the Ordering of Events in a Distributed
System,
Communications of the ACM, vol. 21, no. 7, p. 558-565, July 1978
From: ontolog-forum-bounces@xxxxxxxxxxxxxxxx
[mailto:ontolog-forum-bounces@xxxxxxxxxxxxxxxx] On Behalf Of Pat Hayes
Sent: Sunday, January 11, 2009 11:51 AM
To: [ontolog-forum]; Patrick Cassidy
Subject: Re: [ontolog-forum] FW: Next steps in using ontologies as
standards
On Jan 11, 2009, at 10:18 AM, Pat Hayes wrote:
When you say “Those
various temporal theories can all be expressed in terms of three
concepts: time-point, time-interval and duration.” , what do you mean by
that? Is being “expressed in terms of” used only for
necessary and sufficient definitions?
No, I mean only that each theory uses only those three
terms, or can be reformulated using only those (or in some cases only two of
them.) Of course, since the theories have different axioms, they assign
somewhat different meanings to them.
Thinking more, this isn't really accurate. They all use only
these three classes, but they also use various different relations, such
as the timepoint and subinterval orderings and the various relations between points
and intervals. So perhaps the typical number of concepts is more like six or
seven than two or three.