Re: [NTG-context] Math literal colon

On 20 Jul 2015, at 18:37, Aditya Mahajan wrote:

On Mon, 20 Jul 2015, Hans Aberg wrote:

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On 20 Jul 2015, at 16:40, Aditya Mahajan wrote: On Mon, 20 Jul 2015, Hans Aberg wrote:

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The LaTeX package unicode-math has an option colon=literal, which makes it behave as in math functions (as in example below). Has ConTeXt a similar option? No. You have to use \colon.

It would be nice with such an option, as it helps the readability of the input files.

There are two uses of colon in math, as a relation (in sets \{ x : f(x) = 0 \} and in ratios A:B, etc) and as a punctuation ($f \colon A -> B, etc.[1]). Only one of them can be mapped to the literal :, the other must use a macro name. Knuth chose to map : to the relation and mapped \colon to a punctuation and every other macro package follows that convention.

Right. Perhaps he didn’t use functions much. :-)

It is easy to change the mapping, but if the mapping is reversed, is there is standard name for : as a relation?

It seems that “\:” might be used. I get an error when trying to use it in luatex. But note: In pure math, “:” is also used for projective coordinates, it does not seem to have operator spaces around them. This is what I think is the right look: https://en.wikipedia.org/wiki/Homogeneous_coordinates#Notation There is also Unicode ∶ RATIO U+2236. So a proposal might be to keep \colon, and make a new \ratio for those that want to use the operator : in ASCII. The : without spaces might perhaps be called \proj or something. Looking at https://en.wikipedia.org/wiki/Mathematical_Operators a UTF-8 mapping would be sending U+2236 to \ratio, the operator :. There is no special colon for the other uses, function and projective coordinates, it seems. So the \: might be mapped to \proj or \ratio according to taste.