Dear David Leal, (01)
just a question. You wrote:
---------------------------
> Joe is seeking something simple, and I think that we now have it.
>
> The argument is as follows:
> 1) There is a magnitude_of_quantity (Q3) that is expressed as "1.3 kg".
> This
> is an equivalence class.
>
> 2) My_book is classified as a member of "1.3 kg".
>
> 3) There is a set of mass instances of magnitude_of_quantity, which we can
> call "mass as a class of magnitude". This set is a member of
> kind_of_quantity (as class of magnitude - Q4). (02)
Why don't you regard Q4 as a class-of-equivalence-classes? Mass would then
be the class of all possible equivalence classes of the form 'x kg'. Or
perhaps this is what you want to say with your distinction between set and
class? (03)
Ingvar J (04)
>
> 4) Any quantity of matter is a member of exactly one member of "mass as a
> class of magnitude". Therefore there is a function from quantity of matter
> to "mass as a class of magnitude". We can call this function "hasMass".
>
> 5) The relationship between my_book and "1.3 kg" is an evaluation of this
> function. So in OWL serialised as N3, we have:
>
> :My_book :hasMass [ :expressedAs [ number: "1.3"; reference:
> "kilogram" ] ] .
>
> In this representation:
> - The instance of magnitude_of_quantity is anonymous. It is merely
> necessary
> to specify the quantity_value that expresses it.
> - The instance of quantity_value is anonymous. It is merely necessary to
> specify its number and reference.
>
>
> What do we need in the standard ontology?
> -----------------------------------------
> This example replies upon:
> Q3 - magnitude of quantity - an equivalence class;
> Q4 - kind of quantity (as class of magnitude) - a set of instances of
> magnitude of quantity of the same kind;
> mass - as a member of Q4 and a subclass of Q3.
>
> The definitions of Q3 and Q4 are rooted in the VIM, and therefore we have
> largely met our objective. We can declare that we have won, and go home.
>
> The example also relies upon the function "hasMass". I suggest that this
> function is out of scope because:
>
> 1) It is a derived concept, which is there for implementation purposes
> only.
> The statement about the mass of the book can be made without using this
> function as:
>
> :My_book a [ :expressedAs [ number: "1.3"; reference: "kilogram"
> ] ] .
>
> This is a true statement, but not useful in an implementation. A query
> "what
> is my_book classified as?" is going to return a lot of rubbish.
>
> 2) The function "hasMass" is one of a family of functions such as "has
> mass
> when empty", "has mass when full of oil", "has mass when full of water",
> etc.. The standardisation of these functions is clearly outside our scope.
>
> (Ed says that the discussion of mass does not generalise. We need to work
> on
> this. I think that it does, but only for the quantity mass is a function
> "hasQuantity" widely useful. The function hasLength exists, but it is only
> useful for lines. Instead we use "has height", "has waist measurement",
> etc..)
>
>
> What have we missed?
> --------------------
> We have not specified what is the particular quantity (Q1) or its kind
> (Q2).
> There are different views about this, so lets tackle this later.
>
> The concepts "mass when empty", "mass when full of oil" are all member of
> the box in the straw man UML diagram denoted "generic quantity". These are
> sometimes conveniently regarded as functions, but this is not the only
> approach. Again, lets tackle this later.
>
> Best regards,
> David
>
>
> At 16:05 25/09/2009 -0400, you wrote:
>>PH> ... but we ought to provide some axioms relating our notions
>> > to appropriate higher-level categories, if only in order to provide
>> > a guide to those whose task it is to write such axioms. Can people
>> > use 'mass' as a function on physical objects, for example?
>>
>>
>>YES.
>>"Mass" can be interpreted as a function applied to a physical object.
>>An algorithm that evaluates this function is a weighing procedure.
>>
>>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
>>_______________________________
>
> ============================================================
> David Leal
> CAESAR Systems Limited
> registered office: 29 Somertrees Avenue, Lee, London SE12 0BS
> registered in England no. 2422371
> tel: +44 (0)20 8857 1095
> mob: +44 (0)77 0702 6926
> e-mail: david.leal@xxxxxxxxxxxxxxxxxxx
> web site: http://www.caesarsystems.co.uk
> ============================================================
>
>
>
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> (05)
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