Org syntax: \[ \] as block element instead of inline object

[Max Nikulin]

I like Timothy's idea that \[ \] markup should behave like block-level 
element rather than inline object. On the other hand, Nicolas convinced 
me that the problem is not only with filling paragraphs in Emacs using 
M-q and it requires change of Org grammar. That is why I do not think 
that suggested patch should be applied.

Although Org has its own syntax, \[ \] constructs are added for LaTeX 
snippets, so unless there is a strong reason, such construct should not 
be a surprise for users familiar with LaTeX.

As it pointed out by Nicolas, the following is a compatibility issue 
with such change.

The following will be invalid Org structure, however the problem is 
hidden in the case of exporting to LaTeX:
A \[
  1 \ne 2,
\] B

It should be typed as

A
\[ 1 \ne 2, \]
B

or

A
\[
  1 \ne 2,
\]
B

On 02/10/2021 03:41, Nicolas Goaziou wrote:
> > I wonder, why it is not a block element. As far as I know, the only
> > difference (even in the context of Org) between \(...\) and \[...\]
> > is, that the former denotes inline math and the latter denotes a math
> > block. And at least exporting to HTML (with MathJax) and LaTeX results
> > in a block equation for \[...\].
>
> That's not true. Only some export back-ends can tell the difference
> between \(...\) and \[...\], so in the context of Org, they are the
> same.

Is there a valid use case for that backends, so they should not consider 
\[ \] as a block-level element? Otherwise I would tell that it is a bug 
in that backend and in Org parser.

> > Do you have a short summary or a pointer why \[...\] has been choosen
> > to be an inline element?
>
> Yes: habit. Also, I don't think LaTeX treats it as a block element.
> E.g.,
>
>      text
>      \[1+1=3\]
>      text
>
> is a single paragraph in LaTeX.

It is a single LaTeX paragraphs assembled in vertical mode from parts 
created in horizontal or math mode. Splitting text into lines (in 
horizontal mode) is performed for each part of paragraph independently. 
So LaTeX paragraph is more like "greater element" than just "element". 
There is no of similar concept in HTML + CSS, there are blocks and 
inline parts. Formatting like paragraph indents and vertical spacing 
between paragraphs may be achieved with CSS rules.

Visually formatted paragraph may contain several block-level elements.

P.S. Examples of HTML vs. LaTeX paragraphs in Org export that were not 
intuitive for me:
https://list.orgmode.org/orgmode/sd9h2q$t9a$1@ciao.gmane.io/T/#u