Re: Looking for two mathematical characters

From: Kenneth Whistler (kenw@sybase.com)
Date: Mon Jun 16 2003 - 17:53:44 EDT

  • Next message: Philippe Verdy: "Re: Looking for two mathematical characters"

    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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