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Re: [uom-ontology-std] retitled: magnitude of a quantity

To: uom-ontology-std <uom-ontology-std@xxxxxxxxxxxxxxxx>, ingvar_johansson <ingvar.johansson@xxxxxxxxxxxxx>
From: Pat Hayes <phayes@xxxxxxx>
Date: Mon, 20 Jul 2009 14:09:50 -0500
Message-id: <09299440-CCA0-42FA-8CCD-EE3D570ED289@xxxxxxx>

On Jul 19, 2009, at 4:13 AM, ingvar_johansson wrote:    (01)

> John Graybeal wrote:
>
>> In fact, I'm not even sure how values got to join in with units.  I
>> would have said
>> 0) Units
>> 1) Values with Units
>> because just having units sorted out by themselves -- with URIs for
>> each concept -- enables all sorts of effective tools and toys.
>
> Dave McComb wrote:
>
>> I could get started with level 0.  I must admit though every use
>> case I can think of involves a unit and a value.    (02)

Dimensional analysis? Writing general code to convert between units?    (03)

>
> I would say that it is logically impossible to have a unit without a
> value.    (04)

Its clearly logically possible. Conceptually they seem distinct. The  
idea of the meter, for example, is not the individual measure 'one  
meter', though the two are obviously closely related. I would say that  
'meter' denotes a function from lengths to numbers, and one meter is  
the length, such that the value of that function when applied to it,  
is the number 1:    (05)

(the (x) (= (meter x) 1) )    (06)

And by the way, (= meter metre)    (07)

Pat    (08)

> To have the value 1 is also to have a value. On the other hand, a
> value without a unit is just a pure mathematical number. I think
> Graybeal's distinction should be replaced by the following:
> 0) Base units
> 1) Values of base units.
>
> The value of the base unit is created by a pragmatic choice. It is  
> not to
> be found in mind-independent nature, and it is not necessarily 1.
>
> Best, Ingvar J
>
> -- 
> home page: http://hem.passagen.se/ijohansson/index.html
>
>
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>    (09)

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