# Re: Technical reasons for some options taken on design of MathML

From: Paul Libbrecht <paul@activemath.org>
Date: Thu, 30 Mar 2006 12:56:05 +0200
Message-ID: <442BB945.5050004@activemath.org>

```
juanrgonzaleza@canonicalscience.com wrote:
> For example,
> - what is the argument to use some like
> <apply><divide/><ci>A</ci><cn>2</cn></apply> instead of shorter
> <divide><ci>A</ci><cn>2</cn></divide> ?
>
To be able to speak about the "divide" operation ??
The same has been done in OpenMath btw.
> - What is the reason for
> <apply><plus/><cn>5</cn><cn>8</cn></apply>
> instead of calculator-like
> <apply><cn>5</cn><plus/><cn>8</cn></apply> ?
>
That'd be a bad-thing how would you consider, if the second was true,
the following:
<apply><cn>5</cn><cn>5</cn><plus/><cn>8</cn></apply> ?
????
You definitely need the operation to be at head!
> - What is the reason for
> <msup>base <mrow>index1 index2</mrow></msup>
> instead of base<sup>index1 index2</sup> of SGML/HTML/XHTML/CSS
> or the base^{index1 index2} of TeX systems ?
>
I think Mikko answered this well... you know how high you can put your
exponent...
Note that msup and mfrac, just to name two, are elements that have a
fixed number of arguments... and that has saved me hours of work! They
are the only elements that can be checked for arity at display time. My
generated MathML-p did contain several times expressions such as:
<mfrac><cn>1<cn/><mo>+</mo><mi>2</mi><mi>y</mi></mfrac>
Which are just impossible to parse (where is the denominator?)...
Fortunately, Mozilla prints a bold "invalid markup" which I can catch
quickly instead of trying to guess something as have been doing many
HTML parsers.

earlier, you wrote:
> Unfortunately, the w3c MathML specification does not explain to readers
> the reasons for the several options taken by its authors.
>
I think the spec is already quite complete as is... and it is good to
ask these questions... the mailing-list is archived and also scanned by
people that have questions such as these ones and they often get answered!

Keep asking!

paul
```
Received on Thursday, 30 March 2006 10:56:24 GMT

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