I must admit that I find many of these ontology discussions hard to follow.
They are too abstract for me. (01)
Let me suggest that we need a set of agreed upon use cases. (02)
How will any UoM knowledge structure be used?
I believe that use cases will help define and allow some agreement on
requirements. (03)
What kinds of knowledge do we expect to express?
Let me suggest these (open-ended) categories: (04)
1) At a minimum people want to express physical quantities in databases, as
inputs to and outputs from applications that use this data. (05)
2) Support for units conversion. (06)
3) I have oriented my work towards enabling quantity expression and
mathematical
formula expression. This requires some form of mathematical semantics. (07)
... (08)
N) Reasoning within natural language expressions? (09)
Regards,
Joe C. (010)
Joel Bender wrote:
> Or am I a nominal pragmatist?
>
> In the "What is Mass?" thread there are references to tropes, which was
> a completely new term that I didn't understand until I followed a few
> discussions in the ontolog-forum. Then Matthew West wrote "My lump of
> cheese is a member of the 1.3Kg equivalence class" and it causes me a
> bit of concern.
>
> Neither the use of the term 'trope' nor mapping of a thing like a lump
> cheese into an 'equivalence class' is going to fly very far with
> software engineers, programmers, or architects.
>
> When this standard gets published, I expect that these people will begin
> with the notion (or could eventually be convinced) that properties of an
> object, fields of a structure, and columns of a database table could be
> improved by annotating them with a unit of measure. Having a
> consistent label for the annotation and a consistent way of applying it
> is a good thing, they'll keep reading.
>
> Up front there will probably be some clause that says "how the unit of
> measure is associated with the value is a local matter", so don't expect
> this standard to propose a new kind of property for an object, a new
> type of database column. That leaves "presentation" or "exchange" issues.
>
> So how do I, as a architect, tell my programmers to present the fact
> that my lump of cheese is 1.3Kg rather than 1.3 (un-annotated)? As a
> character string in a comma-delimited text file?
>
> ...,"1.3 Kg",...
>
> How do I do it in XML?
>
> <weight uom:unit="Kg">1.3</weight>
>
> RDF?
>
> :myCheeseLump :weight
> [ rdf:value "1.3"^^xsd:decimal; uom:unit uom-si:Kg ] .
>
> I know that while my database calls it 'weight', it should probably be
> called 'mass', but is that really important? Can I still call it
> 'weight' and take advantage of the standard?
>
> I'm exchanging data with a partner, and while my stuff is in Kg, his
> database uses lbs. How does this standard help me know if Kg can be
> converted to lbs, and how can that be accomplished?
>
> On to the next layer of abstraction.
>
> My database has many tables and many columns, does this standard provide
> a way to say column Y of table X is always Kg?
>
> What if its a count? My transaction database has a QTY column which is
> a count of widgets. Is a 'widget' a proper unit of measure? Can I
> expression "widgets per day" as something I have measured?
>
> Now I would like to improve the way my programmers use values. In some
> cases the programmers have added two values together and they are not
> the same unit, does the standard provide a way of knowing if two
> annotated values can be added? In some cases, like widgets, it is
> required that the values be integers, 1.5 widgets doesn't make sense.
> How can I say that the value is restricted to be an integer?
>
> More generally, how is this standard going move from "trope" to being
> the stimulus motivating systems architects to change their systems
> ...dare I say... tropism?
>
> :-)
>
>
> Joel
> p.s.- while I can't join immediately, I'm looking forward to today's
> conference call
>
--
_______________________________
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
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