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Re: Mathematical selection

From: Paul Libbrecht <paul@activemath.org>
Date: Thu, 30 Mar 2006 22:15:45 +0200
Message-ID: <442C3C71.3060002@activemath.org>
To: Neil Soiffer <neils@dessci.com>
Cc: Public MathML mailing list <www-math@w3.org>

Neil Soiffer wrote:
>
> I assume that by the dual operator "*", you mean "*" in a superscript 
> position such as in x^*.  In such a position, it has no arguments and 
> precedence is meaningless so I don't understand what you are 
> asking/commenting on. 
>
Well... we're getting down to where it shouldn't get... the appearance 
of character.
The * symbol in all the fonts I used every day is high so I'd write V* 
without an exponent. Would such a shape be part of Unicode spec ?
>
> Maybe this exposes just how weak my K-12 education was :-)
>
;-)
>
> FYI:  (as you know) "*" is not usually used for multiplication in 
> typeset math -- &CenterDot; or &times; or &it; are typically used.  
> "*" was included for compatibility with ASCII-based math notations 
> just as ">=" was included.  The operator dictionary does not recommend 
> one form over another and tried to be inclusive as an aid to 
> developers in case those notations were used by authors.
>
Another usage of * which is not a multiplication but a binary operator 
is the pull-back (much used in categories, topology, and differential 
geometry, I agree we leave K-12 here ;-)) or the convolution (which at 
least many electrical engineers use).

Do these all have the same precedence ? Not sure.
I fear Darwinism should suppresses species!

paul
Received on Thursday, 30 March 2006 20:15:57 GMT

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