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RE: What is "f'(x)" as MathML?

From: Robert Miner <robertm@dessci.com>
Date: Fri, 21 Jan 2011 07:49:40 -0800
Message-ID: <40A20C534FFFD5438E1A756DD25234D3016F7878@franklin.corp.dessci>
To: Daniel Marquès Solé <dani@wiris.com>, "J.Fine" <j.fine@open.ac.uk>, <www-math@w3.org>
A problem that comes up with the <mi>f</mi><mo>'</mo><mo> style of markup is that it doesn't accommodate stacked scripts well.  That is, notations like

<msubsup>
  <mi>f</mi>
  <mn>0</mn>
  <mo>&prime;</mo>
</msubsup>

This is a problem for the whole class of characters that notationally function as superscripts, but that Unicode considered to merely be instances of characters that happen to be "pre-shrunk" and raised above the baseline.  MathML 3 terms these characters pseudoscripts, and there are around 20 or so, including various primes and backticks, the degree symbol, asterisk and some others.

I assume that Unicode was forced into considering things like degree and asterisk as pre-shrunk, raised characters by backward compatibility considerations long ago, and merely carried forward that decision consistently.  But given the importance of the stacked script case in practice, it wasn't a very good decision.  To accommodate that case, renders have to special case those characters in some fashion.

Anyway, I just wanted to mention this, since apart from other more theoretical, semantic considerations, in working with STEM publishers using MathML is big work flows, the practical stacked script has been the dominant consideration.

--Robert


> -----Original Message-----
> From: www-math-request@w3.org [mailto:www-math-request@w3.org] On
> Behalf Of Daniel Marquès Solé
> Sent: Thursday, January 20, 2011 9:00 AM
> To: J.Fine; 'www-math@w3.org'
> Subject: RE: What is "f'(x)" as MathML?
> 
> Hello,
> 
> I my modest opinion
> <math><mi>f</mi><mo>'</mo><mo>(</mo><mi>x</mi><mo>)</mo></math>
> 
> Regards,
> 
> Dani
> 
> -----Original Message-----
> From: www-math-request@w3.org [mailto:www-math-request@w3.org] On
> Behalf Of J.Fine
> Sent: jueves, 20 de enero de 2011 15:37
> To: 'www-math@w3.org'
> Subject: What is "f'(x)" as MathML?
> 
> Hi
> 
> Forgive me for asking a question that might already have been answered,
> but what is the 'correct' translation of the TeX notation mathematics
> "f'(x)" into presentation MathML?
> 
> With best regards
> 
> 
> Jonathan
> 
> --
> The Open University is incorporated by Royal Charter (RC 000391), an
> exempt charity in England & Wales and a charity registered in Scotland
> (SC 038302).
> 
> 
Received on Friday, 21 January 2011 15:48:29 GMT

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