[Om] Questions about representing units

Professor James Davenport jhd at cs.bath.ac.uk
Sun Feb 22 04:52:44 CET 2009

On Sat, February 21, 2009 8:16 pm, Christoph LANGE wrote:
> On Saturday 21 February 2009 19:34:45 Professor James Davenport wrote:
>> It's come back to me. The ones we DO want are miles_per_hour etc., since
>> the abbreviation, mph, is non-standard.
> Really?  To my understanding it's wrong to represent such abbreviations on
> the OpenMath level.  And, secondly, I find miles_per_hr in the OpenMath
> CDs, but I don't find any reference to "mph".  So how did you represent
> this abbreviation?
We didn't,because the whole question of "how do we handle abbreviations"
wasn't fully worked out. At the time, DefMP didn't exist, never mind FMP
type="alias" or any of the other ideas now circulating.
> <potential-bias type="omdoc kohlhase ...">
> More generally, probably off-topic for this discussion, but nevertheless
> interesting (IMHO), a comment on what you said about abbreviations in your
> 2008 paper:  I wouldn't agree with a representation of abbreviations by
> introducing additional OpenMath symbols -- your two "alternative
> definition" cases in that paper.  I share your view that "this isn't an
> OpenMath problem".
> You suggested OWL as a solution.  I don't completely agree with that.  OK,
> one
> could introduce a string-valued OWL "datatype property" for annotating
> OpenMath unit symbols with their abbreviation, e.g. leading to an
> annotation like
> http://www.openmath.org/cd/units_imperial1#miles_per_hr
> http://www.openmath.org/ns/unit-annotation#abbrev
> "mph".
> (Recall my OM3 Trac posts about more flexible metadata; within such a
> framework, one could even embed this into an OpenMath CD.)
> But then, we'd require an application to know OWL, or at least this
> particular annotation vocabulary.
True. The OWL suggestion was based on a worldview in which OWL becomes THE
answer, a world view which certainly hasn'tprevailed yet.
> More naturally from my point of view is treating this problem as a problem
> of rendering OpenMath to presentation markup.  For that, our (admittedly,
No - it's a bi-directional problem, I think. If not, then your suggestion
is at least plausible.
> not-yet-standard) approach is defining notations, and we do that by
> mapping
> content markup patterns to presentation markup templates.  That said, we
> could
> easily define a "presentation context" "abbreviated" and then map
> units_imperial1#mile to "mi"
> units_time1#hour to "hr"
> (arith1#divide units_imperial1#mile units_time1#hour) to "mph".
Sorry - I don'tseehow this one works.
> … i.e. solve the problem without introducing an additional symbol.
> </potential-bias>

James Davenport
Visiting Full Professor, University of Waterloo
Hebron & Medlock Professor of Information Technology and
Chairman, Powerful Computing WP, University of Bath
OpenMath Content Dictionary Editor
IMU Committee on Electronic Information and Communication

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