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Re: Accented variables, and cancelling fractions

From: <jpederse@wiley.com>
Date: Thu, 31 Jul 2003 09:37:51 -0400
To: "'MathML list'" <www-math@w3.org>
Message-ID: <OF642B458F.3866F83A-ON85256D74.0049B2F0@wiley.com>

Is the set of combining diacritical marks (Unicode blocks U+0300-036F and
U+20D0-20FF) more appropriate for use as accents (even though most don't
have symbolic names)? There they do have, for example, an under dot
(U+0323) in addition to the over dot. In MathML I suppose it would still
need the <munder> treatment though (outside of <mtext>).

I have a related question: what is the correct way in MathML to tag
"crossed out" parts of fractions, used to indicate terms that have been
cancelled? If it is a single letter or number, then the combining solidus
U+0338 would do the trick, but is there a way to indicate a line through a
whole expression? Should I use
<mrow>...the expression...</mrow><mo>&#x0336;</mo> ?

Thank you.

John Pedersen
Content Systems,
John Wiley & Sons, Inc.

                      "Pepping, Simon                                                                    
                      (ELS)"                   To:       "'MathML list'" <www-math@w3.org>               
                      <S.Pepping@elsevi        cc:                                                       
                      er.nl>                   Subject:  Accented variables                              
                      Sent by:                                                                           
                      07/25/03 08:00 AM                                                                  

In TeX there are specific accents for math: \tilde A etc. In MathML there
does not seem to be such a thing. The msup, mover etc. constructs are much
less specific and much more variable: for example, some people may use
&sim;, others may use &tilde;, for the tilde accent. They seem to encode
idea that one may use any character as a superior to or over another
character. For the well-known math accents that is not appropriate; one
would like to use specific accent characters.

Is there a specific or recommended set of characters which are suitable for
accents on math variables? The symbols in the entities file isodia.ent
http://www.w3.org/TR/MathML2/isodia.html may be a good candidate set. But
they are all spacing accents, which by themselves are already higher and
smaller than a normal character. This situation seems to be identical to
prime, discussed on this list:

As an extreme example, &dot; is dot above. Using it in an munder would not
seem appropriate:
In fact, it works nicely in MathPlayer and Mozilla.

Simon Pepping
DTD Development and Maintenance
Received on Thursday, 31 July 2003 09:43:34 UTC

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