Re: [PATCH] Add support for $…$ latex fragments followed by a dash

[Ihor Radchenko]

Rudolf Adamkovič <salutis@me.com> writes:

> Let $r_i$ denote the \(i\)-th rotation of $t$ with a suffix of $\ell|t|$
> characters deleted, for […]
>
> Me, if I could, I would pay money for this feature, for it would allow
> me to use $$ consistently, focusing on mathematics instead of markup
> idiosyncrasies of "rotation $i$" versus "\(i\)-th rotation".

Would it improve things for you if we change how \(...\) _looks_ in Org
buffers?

The problem with parsing is more than just supporting $i$-th and
similar. For example, AMS style guide explicitly advises against using
$i$-th in favour of $i$th [1]:

    Do not hyphenate “th” expressions: xth, not x-th or xth .

We can theoretically make a change to support "-", but then it will be
logical to support $i$th as well. (If we don't some users will still be
confused after trying to write $i$th and then not getting the expected
results). In this question, it would make sense to implement
all-or-everything approach. Otherwise, confusion (like raised in this
thread) will be inevitable.

However, from point of view of Org mode parser, supporting $i$th is a
nightmare.  Remember that Org mode is _not_ LaTeX and we have to support
a lot more frivolous syntax (even in LaTeX, runaway $ is often a source
of cryptic compilation errors). Currently, we _must_ rely on heuristics
to determine $$-style latex fragments. I do not know any way to support
$$ syntax without creating deviations from LaTeX. Extending the
heuristics will not resolve the underlying ambiguity of $$ syntax, just
hide it within even more obscure cases.

Given the raised concerns, may we solve the issue with too verbose
\(...\) unambiguous syntax using the following approach:
1. Fontify \(...\) replacing the brackets with a single character. For
   example:

      \(...\) -> ⁅...⁆

2. Provide convenient way to input \(\) brackets through
   electric-pair-mode or trough org-cdlatex-mode.

Best,
Ihor

[1] https://www.ams.org/publications/authors/AMS-StyleGuide-online.pdf