As I see it, ontology is about defining things and facts about those
things. By a process of elimination, anything that is not a thing or a
fact is a matter of design and has no place in an ontology. (01)
Mike (02)
ingvar_johansson wrote:
>> The art of ontology is the art of not designing something. What you're
>> suggesting looks a lot more like a design solution than a representation
>> of real things and the way they are.
>>
>> Mike
>>
>
> Please, explain in detail what you mean, and how it affects my proposal.
> In order to talk about the world we have to design concepts, and in order
> to make measurements of properties in the world we have to design scales
> with measurement units. Then linguists can study and represent relations
> between concepts, and UoM ontologists can study and represent relations
> between measurement units. So what?
>
> Ingvar
>
>
>> ingvar_johansson wrote:
>>
>>> A bit below comes a question from an informatics layman.
>>>
>>> Gunther Schadow wrote:
>>>
>>>
>>>
>>>> ingvar_johansson wrote:
>>>>
>>>>
>>>>> one more comment. You asked:
>>>>>
>>>>>
>>>>>
>>>>>> 1 N.m = 1 N.m : true or false?
>>>>>>
>>>>>>
>>>>> and I said 'true' (and so did Pat H). But this does not imply that 1
>>>>> N.m
>>>>> of energy = 1 N.m of moment of force, since energy and moment of force
>>>>> are
>>>>> different kinds of quantities (despite having the same dimension).
>>>>>
>>>>>
>>>> and that's precisely my point and why I disagree with Pat Hayes
>>>> that this is not useful. I was asking if 1 N.m = 1 N.m and
>>>> the answer is ambiguous. The unit is newton-meter, it is not
>>>> newton-meter-of-energy, therefore, I would argue, that the unit
>>>> is the same even if the kinds of quantity are different. Unless
>>>> we agree on this (by either one of us changing our mind) I don't
>>>> see a value at looking at ontological constructs.
>>>>
>>>> I don't want to discuss the N.m issue in particular at this
>>>> time, only that it's pointless to proceed if there is
>>>> disagreement about this matter.
>>>>
>>>> The question remains what we believe jointly that UoM concepts
>>>> should do for us. You may want them to preserve the difference
>>>> between torque and energy, I don't.
>>>>
>>>>
>>> Can't you both cancel and preserve the difference? That is, can't you
>>> have
>>> both an over-arching concept 'nominal newton-meter' and a number of
>>> subsumed concepts such as 'energy newton-meter' and 'torque
>>> newton-meter';
>>> each of which brings in what VIM calls a kind-of-quantity?
>>>
>>> Ingvar
>>>
>>>
>>>
>>>> So the question remains
>>>> open on the list. But there is no point in proceeding if we
>>>> don't agree on this. We might, however, agree if we use these
>>>> example to be more clear about why we have the desire for the
>>>> UoM concepts to do what we want them to do and possibly how
>>>> else we might get our desires fulfilled.
>>>>
>>>> In my experience with dealing with scientific equations and
>>>> computations, the units were incredibly useful for (a) converting
>>>> to a unit that I needed and (b) giving assurance that I probably
>>>> didn't make some gross error in my equations. Thus, in my
>>>> experience with dimensioned terms it does not matter in the end
>>>> whether the m in N.m, was the length of a lever or a distance
>>>> of displacement, that is all in the concerns that led to my
>>>> equations. The units function more like a check-digit at the
>>>> end: if the unit term does not agree with the expected kind of
>>>> quantity, something went wrong in my calculation or the formula.
>>>>
>>>> This is why around UCUM implementation I use the concept of
>>>> a "DimensionedQuantity". A Quantity is any set of values
>>>> where at least some values have a difference operation. A
>>>> DimensionedQuantity is essentially a number with a dimension.
>>>> Such a quantity for example is 16 N.m. Units are themselves
>>>> DimensionedQuantities with a name (and the name can be complex
>>>> such as N.m or even 16.N.m) So, my ontology behaves exactly
>>>> like the symbols that I write on a sheet of blank paper when
>>>> I compute my scientific equations. It does not do more nor
>>>> less than what the units do on paper. I.e., 1 N.m = 1 N.m
>>>> = 1 kg.m2.s-2 = 1 J.
>>>>
>>>> There is nothing you can do to separate these concepts unless
>>>> by assuming into your theory the detail of all of mechanics
>>>> (and all of science) which you can't do.
>>>>
>>>> BTW, it is not true that N.m of torque and joule of energy
>>>> are completely unrelated. Because the torque times angle
>>>> moved is again your energy. Whether or not we maintain a
>>>> dimension for angle in UCUM is also besides this point. Of
>>>> course: by adding more distinct dimensions we may be able
>>>> to preserve more distinctions and by having less dimensions
>>>> we lose distinctions that we can make by just looking at
>>>> number and unit. But because I do not expect much more than
>>>> the function of a "dimensional check digit" and defined
>>>> conversion rates from the units, I can give or take a few
>>>> dimensions without much trouble. The only place were I really
>>>> get into trouble is where we haven't even started to discuss,
>>>> i.e., idiosyncratic "procedure defined units".
>>>>
>>>> regards,
>>>> -Gunther
>>>>
>>>> --
>>>> Gunther Schadow, M.D., Ph.D. gschadow@xxxxxxxxxxxxxxx
>>>> Associate Professor Indiana University School of Informatics
>>>> Regenstrief Institute, Inc. Indiana University School of Medicine
>>>> tel:1(317)423-5521 http://aurora.regenstrief.org
>>>>
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>>>>
>>>>
>>>
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>>>
>>>
>>>
>> --
>> Mike Bennett
>> Director
>> Hypercube Ltd.
>> 89 Worship Street
>> London EC2A 2BF
>> Tel: +44 (0) 20 7917 9522
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>>
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>
>
>
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> (03)
--
Mike Bennett
Director
Hypercube Ltd.
89 Worship Street
London EC2A 2BF
Tel: +44 (0) 20 7917 9522
Mob: +44 (0) 7721 420 730
www.hypercube.co.uk
Registered in England and Wales No. 2461068 (04)
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