From: Jukka K. Korpela (email@example.com)
Date: Thu Dec 20 2007 - 11:59:56 CST
Karl Pentzlin wrote:
> Has it other use than for mathematical logic (especially in Spain)?'
None that I know of, except as the visual indicator of an "optional
hyphen" in the "Show hidden" mode in Microsoft Word. So I have a few
times used it in text when writing something like "you will see optional
hyphens as '¬' characters".
> Was there any specific reason to include it in ISO 8895-1 as one of
> three mathematical symbols besides U+00D7 MULTIPLICATION SIGN and
> U+00F7 DIVISION SIGN?
It's not really even mathematical but logical. Robert Bringhurst's book
"The Elements of Typographic Style" (which exhibits good, but not
perfect, understanding of Unicode), comments that the not sign is
useless without the other logical operators, like the symbols for "and"
and "or", and indeed the not sign looks like an oddity in ISO 8859-1 and
relatives. (Several other ISO 8859 codes also have the not sign in
position AC, but many of them have taken the position to some better
use, mostly for some accented letter.)
But I think there might be an explanation. When the reverse solidus
(backslash) "\" was invented, one of the reasons was that it could be
used together with the solidus (slash) "/" to create two-character
symbols for "and" and "or", namely "/\" and "\/"; see
So one might think that using these notations and the not sign, you
could present the most elementary formulas of sentential logic. Of
course, this is ancient history now.
Jukka K. Korpela ("Yucca")
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