Re: 32'nd bit & UTF-8

From: Hans Aberg (
Date: Wed Jan 19 2005 - 19:28:17 CST

  • Next message: Hans Aberg: "Re: Subject: Re: 32'nd bit & UTF-8"

    On 2005/01/19 20:49, Kenneth Whistler at wrote:

    > It is *not* "a transformation dealing with characters", but a mapping
    > between Unicode scalar values (short hand for, and synonymous
    > to 0000..D7FF, E000..10FFFF) to code unit sequences (bytes in the
    > case of UTF-8, 16-bit units [wydes] in the case of UTF-16, and
    > 32-bit words in the case of UTF-32).

    One might give a purely mathematical definition of a Unicode character,
    freed from any computer representation, as a pair (k, s), where k is an
    integer, and s is string, or finite list, of elements from the set S := {A,
    ..., Z, ' '} (i.e., an element in the free monoid on the set S). Then, UTF-8
    defines a function f: (k, s) |-> (b, s), where b is a finite sequence of
    bytes (math definition omitted), where k in [0, 0x10FFFF]. The
    transformation I spoke about is a function g: k |-> b, where k in [0,
    2^32-1] such that f(k, s(k)) = (g(k), s(k)) when k in [0, 0x10FFFF].

      Hans Aberg

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