From: Kenneth Whistler (kenw@sybase.com)
Date: Mon Jun 16 2003 - 17:53:44 EDT
Patrick Andries asked:
> I'm looking for two mathematical characters.
>
> 1) The canonical one-to-one (injective) mapping;
> is this U+21AA ? Looks like it (no annotation though).
It would probably be best to take this up directly with the
MathML people, but my surmise would be that if an arrow in
the 21XX block looks correct for a particular relation, it
is probably appropriate to use it.
Note that for Unicode 4.0, five different arrows were annotated
for one type of injection or another for z notation, but this
was not among them.
>
> 2) An angle operator (combining mark ?) looking like this _| , where
>
> a )
> n| a ) n occurrences of a
> a ¯ means a )
>
> n|
> obviously a¯ should all be written on a single line.
And Philippe Verdy responded (after a long mathematical analysis):
> If there such character "_|" in Unicode ? Yes.
> With mathematical properties? Yes.
> With the correct semantic? No.
>
> The existing semantic of this mathematical character means "not",
To answer Patrick's follow-up question:
> Which character are you thinking of ? Which code point ?
One would have to surmise that Philippe had U+00AC NOT SIGN in
mind, because of what he claimed it meant. But that character
has the wrong graphic orientation and chirality. Closer would
probably be:
U+2A3C INTERIOR PRODUCT
which has the "_|" orientation. A usage of the symbol (with a
graphic approximation of the intended glyph, parallel to the
"_|" ASCII art version) can be seen at:
http://www.hindawi.dk/books/775945046/B9775945046000361.pdf
What isn't clear to me is whether this interior product symbol
is related to the usage Patrick is talking about,
or would be graphically extended over an expression, as in
Philippe's discussion. For that, again, I think the best thing
would be to follow up directly with the mathematical conventions
experts associated with MathML.
--Ken
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