When composing a new question iver in math.stackexchange, some symbols need an extra \ (backslash) to be rendered correctly:

  1. $ \} $ will not be rendered and needs an extra \ for preview, i.e. $\\}$ is required. Same applies to \{.

  2. $ \| $ will be rendered as | instead of as "parallel" and also needs an extra \ to be rendered correctly.

  3. $\!$ is rendered as !, not as a backthinspace. Similarly, $a\,b$ is rendered as a,b, not as a thinspace between $a$ and $b$.

  4. \\ in environments like \begin{align}...\end{align} don't work, i.e. they don't generate a line break.

Test (one backslash): $ \{ \| \} $ (bogus)

Test (two backslashes): $\\{ \\| \\} $ (rendered as expected in preview)

As far as I remember, I already hit this issue some time ago and was confident that it would be noticed and swiftly fixed, which sadly wasn't the case...

So are there any plans to fix this? Or do they require a local (client) work-around?

According to this answer, the fix is to put spaces around the symbols and / or around math mode and non-math parts; but that doesn't seem to have any effect.

And as you can infer, the same issue is present here on Meta.

  • This happens only with questions and only with the preview.

  • And as it seems, both Meta and MSE are affected.

  • I am currently using FireFox 116.0.3 (64-Bit) for Ubuntu canonical-002 - 1.0.

  • 1
    $\begingroup$ Closing curly brace with single backslash works in answer preview for me here on this page. And I thought backslash+pipe was LaTeX for "half of vector norm", although I learned LATeX here on math.se, so I might have learned a bug instead of the correct way. $\endgroup$
    – JonathanZ
    Sep 26, 2023 at 18:40
  • $\begingroup$ For answers, it works for me, too. It occurs when composing questions. $\endgroup$ Sep 26, 2023 at 19:18
  • 2
    $\begingroup$ Gotcha. And how weird is that? I understand preview vs. posted version, but question vs. answer? $\endgroup$
    – JonathanZ
    Sep 26, 2023 at 19:24
  • 2
    $\begingroup$ What you describe used to be the case many years ago; but it has been a long time since that was the case (in fact, some older posts render incorrectly now because of that). They render correctly for me without the double backslash, both in answers and in questions, both in preview and after posting. So first question is whether the problem you are seeing is just in the preview, or persists after posting (I've had some times issues with stuff showing badly in preview but correctly after posting). But most importantly you need to say what client you are using! Type and version. $\endgroup$ Sep 26, 2023 at 19:59
  • $\begingroup$ (Note the answer you link to is from 2011...) $\endgroup$ Sep 26, 2023 at 19:59
  • $\begingroup$ See related issue discussed here: math.meta.stackexchange.com/q/35946/72031 $\endgroup$
    – Paramanand Singh Mod
    Sep 27, 2023 at 13:32
  • $\begingroup$ @Arturo Magidin: Done. $\endgroup$ Sep 27, 2023 at 15:48


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