Re: Too narrowly defined: DIVISION SIGN & COLON

From: Hans Aberg <>
Date: Wed, 11 Jul 2012 10:36:42 +0200

On 11 Jul 2012, at 02:05, Ken Whistler wrote:

> Incidentally, one of the reasons the set of symbols in the U+2200
> Mathematical Operators block got a somewhat different treatment than
> generic punctuation or other symbols or combining marks, when it comes
> to unification versus non-unification decisions back in the original
> draft charts in 1989 and 1990 had something to do with the intuition
> back then that having unambiguous encodings for the math operators
> would be important for machine processing of mathematical data
> (as in algebra systems).

The spacing in different in mathematics between a colon and the mathematical operator ":", and they are distinguished in TeX. For example, $f\colon A \rightarrow B$ and $x = c:d$.

> It isn't so clear now, in retrospect, whether
> some of the disunifications were a good idea or not. But those
> decisions are what we have inherited in the standard now, for better
> or worse.

When using program like XeTeX or LuaTeX that can use Unicode input text files, it may be desirable to do it by means of different Unicode characters rather than TeX macros. So at least some of those distinctions may be important.

Received on Wed Jul 11 2012 - 03:38:12 CDT

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