On Jul 14, 2009, at 3:14 PM, Martin S. Weber wrote: (01)
> Ed Barkmeyer wrote:
>> (...)
>> By comparison, Martin Weber said:
>>> This is a confusion that should be equivalently confusing
>>> modelled! [i.e.
>>> keep all the overloaded meanings of the term 'quantity' to stick
>>> to BIPM-parlese].
>>
>> I could not disagree more! (But I assume Martin was joking.) Our
>> objective is not to capture the terminological problems in the
>> VIM. The
>> objective of the ontology is to capture the distinct _concepts_ in
>> the
>> VIM (and related references), characterize those concepts, and
>> associate
>> them with suitable terms. Where possible, the terms will be those of
>> the VIM, or something very close.
>
> Actually I wasn't joking. I'm a CS. A CS is a CS or a CS with humor.
>
> IMO the concept of a quantity (by means of the BIPM) refers to
> multiple levels
> of abstractness trickling down to specific things.
>
>> David Leal added:
>>> p.s. The use of one term for objects at two different meta-levels is
>>> familiar to those working with ISO 10303. In ISO 10303-41, the
>>> entity type
>>> *product* is defined as follows: "A *product* represents a product
>>> or a type
>>> of product." (This is not a tautology - the entity type *product*
>>> is defined
>>> using the defined term "product".)
>>>
>>> Ontologically this is not very nice, and as ISO 10303 evolves
>>> towards being
>>> an ontology, it will be good to separate out the two uses.
>>
>> What (I hope) David means is "not very nice" is equating the same
>> model
>> element with two importantly different concepts: a thing (product)
>> and
>> a classification of things (type of product). And no, we don't
>> want to
>> make that mistake with "quantity". (...)
>
> Do we want to have three different "length"s though that all refer to
> different abstract levels, one being the base quantity of the ISQ
> SI; one
> being all measurable lengths including the equivalent quantities
> distance,
> height and so on; one being specific length of things ? (02)
We need to distinguish the following from one another, whatever we
call them. (03)
(1) the dimension that 'length' corresponds to, which is one-
dimensional spatial extent. (This is also the dimension for 'width',
'height', 'distance', 'thickness', etc., so if these are distinct it
must be in some other way than the dimension they identify.) (04)
(2) the property Of a thing called its length. This should be
conceptualized as a function or a property in a suitable formal
description, ie it depends on the thing whose length is being measured. (05)
(3) the class of all possible lengths, ie values of the lengthOf
property. This is a class or a predicate in a suitable formal
description. Its the range of the lengthOf function. It is an element
of the meta-class of measure classes. (06)
(4) the numerical value of a length, using some suitable measuring
scale of lengths. I would suggest conceptulaizing a measuring scale as
a function with domain a measure class and range some totally ordered
measuring set, probably the reals or natural numbers in most cases,
though other choices are possible for eg. approximate measurements. (07)
>
> There is something bitter to bite into at either end and IMO the
> established
> bitter is preferable, isn't it? Adding another set of definitions
> that then
> are satisfying the ontological community but confusing the physicists,
> mathematicians (who happily deal with ambiguities like these) and
> computer
> scientists (whose daily bread often is structural recursions like
> these) (08)
Speaking as a computer scientist, we are extremely leery of
nonterminating structural recursions, and this looks like one to me. (09)
> ... is
> that better? The strength of all these standards is their domain of
> application, where at latest people from other fields have to get
> involved.
> Confusing them and breaking their language habits isn't particularly
> helpful (010)
Not gratuitously, but if we are to write a coherent ontology we may be
obliged to be pickier than many existing glossaries were designed to
be. For example, we cannot confuse a property with a class, even if we
use the same name for both of them. (011)
Pat (012)
> [again IMO].
>
> Regards,
>
> -Martin
>
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> (013)
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