Re: domain questionnaire

>>Weight in lbs and *mass* in kgs are clearly different domains. However,
 mass
>>in grams and mass in kgs could be the same domain with two different
>>representations. Mass would have the same operators defined regardless of
>>representation.
>
>Well, your answer depends on Metric System we chose. In other words, in old
>English system we have dozens of domain.

Actually, the British Imperial system of measurement has no more and no fewer domains than Systeme Internationale.

> In <cm,g,sec> three only.

I get a perverse sense of pleasure rewriting that as <rod,slug,fortnight>

The domains are still distance, mass and time regardless of representation.

><60|kg> = <135|lb>
>
>which is too similar to scalar product to ignore it.

You assume that the scalar is constant, and it is not. The equation you present holds true at certain points on the face of the earth, but certainly does not hold true anywhere on the surface of the moon.

Nothing prevents an operator from converting among domains. One can define a WeightOnEarth operator to calculate the weight on earth of a known mass. Additionally, one can define a WeightOnMoon operator to calculate the weight on the moon of a known mass.

More generally, one can define a GravitationalForce operator on any two masses and a known distance between them. To achieve physical independence, the database should manipulate the resulting force values with equivalent results regardless of representation in pounds or newtons or any other measure of force. Received on Sat Feb 24 2001 - 18:52:46 CET