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RE: When to stretch parentheses

From: Bernhard Keil <Bernhard.Keil@soft4science.com>
Date: Fri, 30 Jan 2004 11:52:29 +0100
To: <www-math@w3.org>
Cc: <Vincent.Quint@inrialpes.fr>
Message-Id: <20040130105048.4BDC5880280@egp.w3.org>

In my oppinion there may not be a difference whether you have:
<math xmlns="http://www.w3.org/1998/Math/MathML" display="block">
      ..        some stuff 


<math xmlns="http://www.w3.org/1998/Math/MathML" display="block">
    ..  some stuff 

furthermore <math> should behave in the same way as <mrow>.

So I would say Amaya is right in this case.

Bernhard Keil

-----Original Message-----
From: www-math-request@w3.org [mailto:www-math-request@w3.org] On Behalf Of Vincent Quint
Sent: Friday, January 30, 2004 11:37 AM
To: www-math@w3.org
Cc: Vincent.Quint@inrialpes.fr
Subject: When to stretch parentheses

An user of Amaya reported recently an interesting case where Amaya and Mozilla do not render an expression the same way. I checked
the spec and I am not sure how to interpret it to decide who is right.
Here is the case:

<math xmlns="http://www.w3.org/1998/Math/MathML" display="block">

In Amaya, the parentheses have the same height as the fraction, while in Mozilla they are much smaller and have the same height as
the characters "CM" they enclose.

So, I checked the MathML 2.0 spec (2nd edition).

Section of the MathML 2.0 spec (2nd edition) "Vertical Stretching Rules", first bullet, says:
"If a stretchy operator is a direct sub-expression of an mrow element, ....then it should stretch to cover the height and depth
(above and below the axis) of the non-stretchy direct sub-expressions in the mrow element..."

I guess this is in favor of Mozilla: the stretchy operators are not children of an mrow element, but children of a math element.

But, reading the spec further, section 7.1.2 "The Top-Level math Element", 3rd paragraph says:
"The math element can contain an arbitrary number of children schemata.
The children schemata render by default as if they were contained in an mrow element."
(here, I suppose that "schemata" means "elements", and that "children"
means the same as "direct sub-expression" in section

This seems to be in favor of Amaya.

Is my reasoning right? Or should Amaya do the same as Mozilla?

I should add that if you introduce an mrow element as a child (or direct sub-expression) of the math element, to enclose all the
contents of the original math element, both Amaya and Mozilla do the same: they display large parentheses.

Thanks for any advice,


Vincent Quint                       INRIA Rhône-Alpes
INRIA                               ZIRST
e-mail: Vincent.Quint@inria.fr      655 avenue de l'Europe
Tel.: +33 4 76 61 53 62             Montbonnot
Fax:  +33 4 76 61 52 07             38334 Saint Ismier Cedex
Received on Friday, 30 January 2004 05:51:13 UTC

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