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Re: Accents in the operator dictionary

From: Neil Soiffer <neil.soiffer@gmail.com>
Date: Wed, 21 Apr 2010 15:15:01 -0700
Message-ID: <s2qd98bce171004211515ybc97704zd31fa09ced55776d@mail.gmail.com>
To: Frédéric WANG <fred.wang@free.fr>
Cc: "www-math@w3.org" <www-math@w3.org>
2010/4/21 Frédéric WANG <fred.wang@free.fr>

>  So questions/remarks:
> 1) What is the rationale for defining most accents as "postfix" operators?

I don't know the rationale, but I can guess... it is probably some holdover
from when combining chars were used for accents (even though they are not
supposed to be used as combining chars).  I was going to say that some, such
as U+02C6 are often interchangeable with their combining char "equivalents"
(eg, U+0302 in this case), but U+0302 is not listed as stretchy (which seems

2) The rules for determining the form and the operator dictionary make this
> two cases behave differently:
>   - low line: <mover><mi>abcdef</mi><mo>_</mo></mover> (form = infix, so
> not stretchy)
>   - overline: <mover><mi>abcdef</mi><mo>&#x203E;</mo></mover> (form =
> postfix, so stretchy)

I agree that "low line" seems wrong.

> 3) Why is "check mark" a stretchy accent (or even just a mathematical
> operator)? Is it related to \widecheck (caron) or square root?

I'm not sure when we decided to eliminate it, but "check mark" is not in the
current draft.  See

Note:  the Operator Dictionary is non-normative, so you can ignore it as you
please.  Nevertheless, it would be good to remove as many errors as possible
from it.  We'll discuss these problems at our next MathML meeting.  If you
find more, please send them along.

Neil Soiffer
Senior Scientist
Design Science, Inc.
~ Makers of MathType, MathFlow, MathPlayer, MathDaisy, WebEQ, Equation
Editor ~

> --
> Frédéric Wang.
> www.maths-informatique-jeux.com
> www.maths-informatique-jeux.com/international
Received on Wednesday, 21 April 2010 22:37:45 UTC

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