RE: Why does EULER CONSTANT not have math property and PLANCK CONSTANT does?

From: Philippe Verdy (
Date: Wed Jul 28 2010 - 15:17:10 CDT

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    "Murray Sargent" <> wrote:
    > Alex notes "Operands are not operators, e.g. in a+b, a and b are operands,
    > + is an operator."

    Not always true, this depends on the domain of definition, see below,
    and all operators can also be themselves operands of another operator.
    The generic term for them should be "functional objects". (with the
    same assumption made in computer "functional languages" that use this

    All these functional objects can be considered as constants (or
    values) or as functions modifying the nature or value of the
    surrounding functional objects to create a new functional object as
    the result of their combination. Whever they are constant or not
    depend on the domain of definition (which is not always exposed in all
    formulas, and often implied by the context.

    > I'm sure Karl Williamson knows that, but the mathematical alphanumerics also
    > aren't operators and they nevertheless have the math property. We need to change
    > the description of the math property to include all characters that are used
    > primarily for math and the EULER CONSTANT is such a character.

    The important word of your sentence is "primarily", which just means
    "mostly for maths" but it should be "for scientific formal notations",
    and not for written orthographies of humane language.

    Maths can use any character in the UCS it wants (or more exactly any
    grapheme cluster that can be built with UCS characters, plus a few
    specific combining characters).

    And it will continue to create new symbols, and there are certainly
    many of them that have still not be discovered in some books or
    scientific paper, that will be encoded later).

    Given that also the General category is stable (and also th fact that
    some humane orthography may choose to borrow some symbols currently
    encoded as Maths symbols within its alphabet, or a convenient
    abbreviation signs), this general category is the wrong tool for us.

    So we may need a custom property (but NOT subject to the stability
    policy) to reference characters that are CURRENTLY considered as NOT
    being used in humane languages, but mostly for mathematic/scientific
    notations, even if these lette-like symbols were created from a script
    for humane languages : they are used only for their symbolic value
    (and do not obey to the linguistic rules such as collation mappings,
    case mappings...). The hbar symbol is such a character.

    Such a property would be useful to exclude, in an implementation of a
    specific version of Unicode, these characters from normal linguistic
    processing, in order to protect them from alteration. And it would
    also be useful if ever, later, some humane language starts getting
    written using the symbol, and starts applying linguistic features such
    as collation mappings and case mappings :

    In that case the symbol should remain stable, and the linguisitic
    letters should be encoded separately, unless there's evidence that too
    many texts are already using the maths symbol directly (in which case,
    this symbol will be removed from the custom "scientific-only" category
    defined by the custom (non stable) property.

    Note that in maths, there's no really any distinction between
    operators and operands. They are just symbols having a functional
    behavior and an implied associativity (on left or right, or both,
    depending on the notation used). It's impossible to predict the
    associativity and use of any symbol without knowing the context of
    use, and without knowing the domain of definition of these "functional


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