[dsdl-discuss] Re: Numbers and units

Eric van der Vlist wrote:

> If we accept the notion of a transformation between the parsed and
> lexical spaces, wouldn't MathML be a good target as lexical space?

Just some pointers...

It appears that MathML doesn't directly support units [1] (it's MathML,
not PhysML :-) ), but that workarounds have been proposed [2] and some
work mentioned [3] on a mailing list from the Nasa.

[1] http://lists.w3.org/Archives/Public/www-math/2001Apr/0013.html
[2] http://lists.w3.org/Archives/Public/www-math/1998Jan/0020.html
[3] http://pioneer.gsfc.nasa.gov/xml/internal/mail/mhonarc/xml/msg00071.html

Using the workaround mentioned in [2] and MathML content markup [4] on
the exemple given by Rick:

<dsdl:number unit="dollars_per_cubic_litre">15</dsdl:number>

could be:

<dsdl:value xmlns="http://www.w3.org/1998/Math/MathML">
  <apply>
   <times/>
   <cn>15</cn>
   <apply>
    <divide/>
    <ci type="dsdl-unit">dollar</ci>
    <apply>
     <power/>
     <ci type="dsdl-unit">dm</ci>
     <cn>3</cn>
    </apply>
   </apply>
  </apply>
</dsdl:value>

Even if we would probably want to define shortcuts, this would have the
benefit of relying on something which is solid and already implemented
in libraries and this neatly defines the relation between the units.

[4] http://www.w3.org/TR/MathML2/chapter4.html

Eric

-- 
See you in San Diego.
                                http://conferences.oreillynet.com/os2002/
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Eric van der Vlist       http://xmlfr.org            http://dyomedea.com
http://xsltunit.org      http://4xt.org           http://examplotron.org
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