2012-07-09 8:19, Leif Halvard Silli wrote:
Unicode does not acknowledge
* that the DIVISION SIGN in the (human) mathematical notation of
at least one language (Norwegian) functions as a stylistically
distinct MINUS sign.
* that the COLON sign in the mathematical notation of many
languages functions as a DIVISION sign.
It sufficiently points out that such phenomena exist, in this general
statement, among other things:
‘Other Basic Latin Punctuation Marks. The interword punctuation marks
encoded in the Basic Latin block are used for a variety of other
purposes. This can complicate the tasks of parsers trying to determine
sentence boundaries. As noted later in this section, some can be
used as numeric separators. Both period and U+003A “:” colon can be used
to mark abbreviations as in “etc.” or as in the Swedish abbreviation
“S:ta” for “Sankta”. U+0021 “!” exclamation mark is used as a
mathematical operator (factorial).’
(in “Other Punctuation”, under 6.2 General Punctuation, at
http://www.unicode.org/versions/Unicode6.1.0/ch06.pdf).
It would be unrealistic to try to list down all the possible ‘cross-use’
of punctuation characters as mathematical operators or the varying
semantics of mathematical operators, as these vary by culture, by branch
of mathematics or sciences, by school, etc.
I. "Division-minus"
[…]
[Translation:] "In the formulas, the minus sign ÷ (instead of -)
is used to avoid confusion with the hyphen."
Such practice exists in other cultures too. In Finland, it is still used
in commercial contexts, though not approved by national standards.
Some
might say that we are just using the COMMERCIAL MINUS (⁒).
No, it is a different character.
II. Division as colon
[…]
A very quick browse of Wikipedia showed me that the
colon as division sign is common in Ukraine, Russia, Sweden and Germany
too.
Yes it is, though it is sometimes difficult to distinguish such usage
from the use of the colon in expressing ratios. By the way, somewhat
strikingly, the ISO 80000-2:2010 standard says (clause 2-9.6): ‘For
ratios, the symbol : is also used.’ using U+003A COLON and not U+2236
RATIO (without identifying the character by Unicode number, as it
usually does, but still).
III. Conclusions: Proposal for next Unicode update
Proposal 1:
EITHER division sign should be renamed to division-minus sign.
OR a new "double dotted minus" character should be added.
Proposal 2:
EITHER the COLON should be baptized colon-division character.
OR a new 'division colon' should be added.
Unicode names will never be changed, see
http://www.unicode.org/policies/stability_policy.html
No argument based on a name being too vague, too broad, too narrow,
misleading, outdated, or plain wrong, no matter how convincing, can
change this. Unicode names should be regarded as immutable alphabetic
(or alphanumeric) identifiers rather than names proper, though in most
cases, the Unicode name reflects the meaning and use of a character.
Adding new characters would be possible in principle, but hardly
realistic or useful in this case. They would not change the bulk of
existing data that uses existing characters, and they would just add to
the confusion rather than remove it.
It would be possible, and probably useful, to add annotations to the
code charts, describing that COLON is also used to denote division and
DIVISION SIGN is also used to denote subtraction. But the annotations
would need to be very short.
Yucca
