Re: symbols/codepoints for necessity and possibility in modal logic

From: Ilya Zakharevich <>
Date: Mon, 29 Jul 2013 17:32:04 -0700

On Fri, Jul 19, 2013 at 04:00:26AM -0700, Stephan Stiller wrote:
> >I'd consider U+22C4 DIAMOND OPERATOR as wrong because it is used
> >as a binary operator

> I'm thinking that "binary infix symbol" and "unary prefix symbol"
> might be appropriate terminology too.

> >which has a very different spacing than the unary modal operator
> >needed here

> The idea that a math symbol has inherent spacing is popular in the
> LaTeX community, though I don't know where else this view exists.

And there is a reason for this “popularity”: having the default
“math-type” for each symbol (overridable if needed) is THE idea which
makes the input of math tolerable in TeX. I’d love to have
math-as-Unicode-text input as easy as math-in-TeX.

  [And, BTW, it is not LaTeX, but the TeX’s core which enables this.]

As far as I can see it, one needs just a couple of bits of info per
math character to support this (since the Unicode repertoir ALREADY
HAS the needed duplication of the symbols which may be used in several
different ways).

  [TeX has many different classes; but distinction between many of
   them is not needed with Unicode. For example, the difference
   between binary-relation and binary-operator is that one of them is
   vertically centered about the math-centerline. Such stuff should
   better be dealt with in fonts, not in character repertoirs.]

However, the major possible problem is that in TeX, this feature is so
powerful because of its interplays with borders of {}-boxes (the
“binaryOp” symbol is visualized differently inside the box that it is
at the box’ boundary). And {-and-} become invisible in the output of
the TeX renderer.

If there were a nice way to use some partially-invisible (;-) markers
( instead of TeX's {} ) in “plain text”, this would make the stuff
so easy! But I have no clue how to make this tolerable in BOTH
for-input and for-reading modes.

Received on Mon Jul 29 2013 - 21:31:23 CDT

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