# Re: [mathjax-dev] Embellished operators

From: Patrick Ion <ion@ams.org>
Date: Thu, 23 Feb 2012 11:42:11 -0800
Message-ID: <4F469693.1010006@ams.org>


I am puzzled that it would be thought that the base, the first argument of
an element of type  <mover>, <munder> or <munderover> might be expected
to change its size automatically depending on the embellishment.  That
seems to be what's being asked for in the examples.  If that isn't the
intention
then I think the sizes to be expected are already well defined by the
default
sizes of the construction's base elements.

See
http://www.w3.org/TR/MathML3/chapter3.html#3.1.3.2

Patrick

P.S.  Murray's first message and example displayed perfectly for me in
Thunderbird
10.0.2 on Mac OS X 10.7.3.

On 2/23/12 9:11 AM, Paul Topping wrote:
>
> I think you have touched the tip of an iceberg with your observations
> here. Robert Miner and I had many discussions of problems like this.
> Presentation MathML's domain of description tries to allow precise
> formatting via specific dimensions and font and character choices as
> well as logical description of math constructs. It always seemed to me
> to be playing with fire. Left up to me, I would have had MathML
> elements and attributes map to concepts in math's visual grammar in
> order to allow the formatter to do a better job. Unfortunately, this
> places a large burden on the author to get it right, something that is
> a big problem for Content MathML.
>
>
>
> Paul
>
>
>
> [mailto:mathjax-dev@googlegroups.com] *On Behalf Of *Frédéric WANG
> *Sent:* Thursday, February 23, 2012 1:02 AM
> *To:* www-math@w3.org; mathjax-dev@googlegroups.com
> *Subject:* [mathjax-dev] Embellished operators
>
>
>
> Hi all,
>
> I'm thinking again about the rules for embellished operators and it
> seems to me that some elements are particular. For example if we ask
> how to determine the stretching of something like:
>
> $> <mover> > <mo>&#x2192;</mo> > <mtext>over</mtext> > </mover> >$
>
> The obvious answer is that the arrow should stretch to cover the over
> script. OK. However one can also say that the <mover> is an
> embellished element as a whole. Since is has no siblings, the arrow
> should have its default size.
>
> To give slightly less trivial examples, what should be the size of the
> arrows (100px or 200px?) in these examples:
>
> $> <mover> > <mspace width="100px"/> > <munder> > <mo>&#x2192;</mo> > <mspace width="200px"/> > </munder> > </mover> >$
>
> and
>
> $> <mover> > <mspace width="200px"/> > <munder> > <mo>&#x2192;</mo> > <mspace width="100px"/> > </munder> > </mover> >$
>
> An example with vertical stretching rules:
>
> $> <mrow> > <mspace height="50px" depth="50px"/> > <mrow> > <mo>|</mo> > <mspace height="100px" depth="100px"/> > </mrow> > </mrow> >$
>
> (I wonder if an attribute like embellishedop = "false" could help to
> prevent this kind of ambiguity?)
>
> I noticed this because implementing the complete embellished op rules
> caused a regression in Mozilla with MathML code generated by MathJax:
> https://bugzilla.mozilla.org/show_bug.cgi?id=687807
>

Received on Thursday, 23 February 2012 19:42:41 UTC

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