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Re: How to use CDBase URIs in Content MathML?

From: David Carlisle <davidc@nag.co.uk>
Date: Mon, 12 Jul 2010 15:14:55 +0100
Message-ID: <4C3B235F.7000405@nag.co.uk>
To: Christoph LANGE <ch.lange@jacobs-university.de>
Cc: Urs Holzer <urs@andonyar.com>, "www-math@w3.org" <www-math@w3.org>
On 12/07/2010 14:30, Christoph LANGE wrote:

> OK, but I'm still confused:  How would I translate the following to Content
> MathML?
>    <OMA>
>      <OMS cdbase="http://example.org/cd" cd="foo" name="bar"/>
>      <OMS cdbase="http://somewhere.com/cd" cd="foo" name="baz"/>
>      <OMS cdbase="http://frobnitz.org/cd" cd="foo" name="fnord"/>
>    </OMA>
> </OMOBJ>
> I.e. what do I do when one formula uses symbols from CDs that have the same
> relative name but under different CDBase URIs?
> And why is there no csymbol/@cdbase?

We went through 1001 permutations of specifying how cdbase and inherited 
attributes and compatibility with mathml2 markup were supposed to work 
and in the end came to the version in the current draft (earlier drafts 
before the 1st last call had different variants as I recall)

cdgroup files dont currently allow aliasing[although see below] so 
currently you would need to set up the alias externally, that is you 
could have the mathml

<math cdbase="http://example.com/mycdgroup.xml">
     <csymbol cd="foo1">bar</csymbol>
     <csymbol cd="foo2">baz</csymbol>
     <csymbol cd="foo3">fnord</csymbol>

with the mycdgroup.xml group file referring to renamed copies of the 
original cd files (either actual copies or some kind of server redirect 
set up at example.com.

the cdbase property is an optional openmath property in openmath2 and 
not there at all in openmath 1, and while it's useful as a location aid 
to find cd files I've never seen it used in practice to disambiguate cd 
files of the same name. The OpenMath CD review system has always assumed 
so far that any public CDs have unique names (hence the numbered names 
arith1, arith2 etc to allow easily naming variants)

so while the need to rename the files is a theoretical wart hopefully it 
isn't an issue in practice. Even in the OM syntax, if there is a real 
possibility of those three cds being used together, then giving them 
different names would probably be a good idea.



Arguably cdgroups do allow aliasing as the OM standard never actually 
says that the CDName and CDURI in a cdgroup file have to match up, so if 
you were to take a forgving interpretation of


then you could mark up your example as above but instead of 
copying/redirecting the files at the http server level you could specify 
it in the cdgroup file as



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Received on Monday, 12 July 2010 14:15:24 UTC

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