Re: math alphabets, WAS: Proprietary Card Decks

From: Hans Aberg (
Date: Fri Apr 15 2011 - 15:29:23 CDT

  • Next message: Asmus Freytag: "Re: math alphabets, WAS: Proprietary Card Decks"

    On 15 Apr 2011, at 21:46, John W Kennedy wrote:

    >>> For example, a/b might be written like that, but it might be written (still inline) with 'a' over 'b' and a horizontal stroke between. In addition, there is "a over b" which does not have such a stroke (but normally parenthesizes). So one might have a character telling that two parts should be grouped over each other.
    >> Just FYI, that distinction is presentational, not semantic, where fractions are concerned.
    > Actually, it's semantic:
    > a+b
    > ---
    > c+d
    > is not equal to:
    > a+b/c+d

    This last one should be written (a+b)/(c+d). When using a two-dimensional layout, one reduces on the number of parenthesizes needed, which is an advantage, making it more readable. When parsing a formula in computer language, one typically constructs an AST (abstract syntax or semantic tree), and from that, it is not difficult to figure to render it with a minimal number of parenthesizes. Parenthesizes can be semantic, for example f^(k) (f superscripted with (k)) might denote the n-th derivative, while f^k the n-th composite or power of f.

    If one does not want automatically the minimal number of parenthesizes, then one needs some other way to indicate groupings.


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