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Re: MathML Content and Operators

From: David Carlisle <davidc@nag.co.uk>
Date: Tue, 14 Jun 2005 17:58:39 +0100
Message-Id: <200506141658.RAA27539@penguin.nag.co.uk>
To: maths@mathsonly.com
CC: www-math@w3.org



Thanks for your comments.

In general the way to extend teh reah of content mathml is to use 
<csymbol definitionURL="some place with a definition in a language of
your choice">something</csymbol>
A symbol introduced like this may be used with <apply> for any kind of
term construction, even if it isn't strictly function application.


However in at least some of your cases, I think the existing diff and
partial diff are sufficient.

I would mark up your first one as follows:


<math xmlns="http://www.w3.org/1998/Math/MathML">
  <apply><eq/>
  <apply><diff/><ci>f</ci></apply>
  <apply><plus/>
    <apply><partialdiff/>
     <bvar><ci>x</ci></bvar>
     <ci>f</ci>
  </apply>
    <apply><partialdiff/>
     <bvar><ci>x</ci></bvar>
     <ci>f</ci>
  </apply>
</apply>
</apply>
</math>



Mozilla (using the stylesheets available at http://www.w3.org/Math/XSL
renders that as

f' = d^1/dx f + d^1/dy f

(where the d's are partial diff operators)

mathplayer (which can natively render content mathml) renders it as


f' = d/dx f + d/dy f

The superscript 1 in teh mozilla rendering is just a suboptimal choice
in ctop.xsl which I should fix when I next update it: It ought to test
for the case 1 and omit the explict superscript. However it's no wrong,
I think, justa bit ugly.

Both renders use a prime rather than a prefix D operator to render diff
(if no explict bound variable is specified) again this is essentially a
notaional choice, which could be varied y a simple change to the
stylesheet, or by supplying a presentation mathml rendering to the
diff operator by wrapping it in a semantics element.

An essentially unrelated comment on your presentation mathml I
don't think you should use InvisibleTimes between the d and x in dx.
I tend to use no operator at all, but wrap them in an mrow to keep them
together <mrow><mi>d</mi><mi>x</mi></mrow>.

For the delta operator I'd se
<csymbol with a definitionurl to some definition of the operator.

> which by default renders in normal (not italic) text when converted to
> <mi>&delta;x</mi>.

that is the wrong conversion (it would be upright as it's a two letter
identifier in that form) You don't want a two letter identifier, you
want two one letter ones (each of which will be italic by default)
<mrow><mi>&delta;</mi><mo>&af;</mo><mi>x</mi></mrow>


David


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Received on Tuesday, 14 June 2005 17:39:08 GMT

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