On Jul 14, 2009, at 4:33 PM, Dave McComb wrote: (01)
> Yes. This is what I was saying.
>
> So what do we call the "52 inches" " a quantity value that expresses a
> magnitude without reference to a particular quantity"? does this
> have a name?
>
> And I guess I'd continue where I was going with the thought about
> "comparable"
>
> I think it takes more than being of the same kind to be "comparable"
> if by being comparable we mean either that one is greater than the
> other, or that they have a scalar relationship (Jupiter is 2 million
> times as far away as your chair). Seems to me to be comparable we
> need some unit in common and a conversion to it. (02)
Not at all. I can hold up two pieces of wood and say, this one is
three times as long as that one. That makes perfect sense without
mentioning units. (Yes, you can say that this is treating the shorter
length as a 'unit' in a sense, but that sense isn't the usual one of
"unit".) (03)
>
>
> Put another way, I think a furlong and a rod are both measures of
> length. However I can't compare them until I can covert measures in
> one either to the other or to something in common. (04)
You can't do the actual calculation until you have that, but you can
say that there is some number N such that one of them is N times the
other. And that is all the 'comparable' you need for the concepts to
be defined. That is exactly sufficient and necessary for them to be of
the same dimension. (05)
>
> Am I missing something here? (06)
I think you are getting epistemic notions muddled with ontological ones. (07)
Pat (08)
>
>
>> -----Original Message-----
>> From: uom-ontology-std-bounces@xxxxxxxxxxxxxxxx [mailto:uom-ontology-
>> std-bounces@xxxxxxxxxxxxxxxx] On Behalf Of Ed Barkmeyer
>> Sent: Tuesday, July 14, 2009 2:35 PM
>> To: uom-ontology-std
>> Subject: Re: [uom-ontology-std] VIM definitions
>>
>> Dave McComb wrote:
>>> I took it to mean they were making a distinction between a
>> particularly
>>> measured thing (Johny is 4 feet tall) (which we call a measure)
>>> and a
>>> reference (you must be 52 inches tall to ride on the Thunder
>>> Mountain
>> Ride).
>>> In the second case nothing was measured, someone just made up a
>> reference
>>> value.
>>
>> I don't think that is what is being distinguished in the secton of
>> the
>> VIM that David and Martin pointed to. The distinction in Dave's
>> example
>> is the one I was making between a 'particular quantity' and the
>> abstraction of it that I attributed to the VIM term 'magnitude of a
>> quantity'. The "52 inches" is a quantity value that expresses a
>> magnitude without reference to a particular quantity.
>>
>>> The other distinction they were calling out "quantity in a general
>>> sense" seems to me is just the TBox for the particular "dimension"
>>> (i.e. "length")
>>
>> Yes. It is a T-box/class/category of particular quantities.
>>
>>> The points about being place in order, and grouping seem to refer to
>>> the "dimension" (we can compare the length of the Themes to the
>>> distance to the sun because they are both measures of distance
>>> (or have dimension "length"
>>
>> Yes.
>>
>>> or even better both have a base unit of "meter" which really makes
>>> them comparable)
>>
>> "comparable" is a source of confusion. The distance from the Sun to
>> Jupiter is "comparable" to the distance from my chair to the door,
>> full
>> stop. That is because they are both quantities of the "length" kind.
>> If one is expressed in astronomical units and the other in metres,
>> the
>> _quantity values_ are not directly "comparable" numerically --
>> comparing
>> the "numbers" is only meaningful when the "units" are the same.
>>
>> (I think this is what Dave was saying.)
>>
>> -Ed
>>
>> --
>> Edward J. Barkmeyer Email: edbark@xxxxxxxx
>> National Institute of Standards & Technology
>> Manufacturing Systems Integration Division
>> 100 Bureau Drive, Stop 8263 Tel: +1 301-975-3528
>> Gaithersburg, MD 20899-8263 FAX: +1 301-975-4694
>>
>> "The opinions expressed above do not reflect consensus of NIST,
>> and have not been reviewed by any Government authority."
>>
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>
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> (09)
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