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Representing complex variable names in Content MathML

From: Robert Muetzelfeldt <r.muetzelfeldt@ed.ac.uk>
Date: Mon, 10 Nov 2008 14:13:26 +0000
Message-ID: <49184186.7070803@ed.ac.uk>
To: www-math@w3.org

Helo,

I am in touch with a group (CF-metadata) [1] that is responsible for 
defining "standard names" [2] for variables in models and datasets 
within the climate change modelling community.  The goal is to improve 
shareability of data between groups by associating standard metadata 
with the variables in each dataset.   A standard name, such as 
"air_temperature_at_sea_level", is a text string generally composed from 
basic terms according to some rather informal guidelines.   I am 
exploring the development of a markup language to capture the structure 
of such terms, in a way analogous to the relationship between plain-text 
mathematical expressions and MathML.

As it happens, some of the terms that can be used to construct standard 
names are mathematical, e.g.:
  ratio_of_X_to_Y
  log10_of_X
  derivative_of_X_wrt_Y
where X and Y are themselves standard names.  So potentially a standard 
name could be
  ratio_of_pressure_to_log10_of_derivative_of_temperature_wrt_time
which could be directly represented in Content MathML.

The problem is that the variables are frequently complex terms: e.g. 
temperature_at_sea_level, or at least should be represented as such (to 
avoid a huge proliferation of terms in a controlled vocabulary, and to 
capture the inherent structure of the term).   Therefore, rather than 
using a simple <ci> element for a term
   <ci>temperature_at_sea_level</ci>
the ideal approach is something like:
   <ci>
      <standard_name xmlns="...">
         <base_quantity>temperature</base_quantity>
         <location>sea_level</location>
      </standard_name>
   </ci>

As I understand it, this is not legal in MathML.  So the alternative 
seems to be to use the <semantics> element:
   <semantics>
      <ci>xxxx</ci>     [Could be 'temperature_at_sea_level', but no 
real point, so use dummy content.]
      <annotation-xml encoding="Variable Markup Language">
         <standard_name xmlns="...">
            <base_quantity>temperature</base_quantity>
            <location>sea_level</location>
         </standard_name>
      </annotation-xml>
   </semantics>

Not very pretty, but is this the best solution to the problem?

Thanks!
Robert Muetzelfeldt


[1] http://cf-pcmdi.llnl.gov/
[2] http://cf-pcmdi.llnl.gov/documents/cf-standard-names









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Received on Monday, 10 November 2008 14:14:22 GMT

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