When I type braces in math mode in a post, like $\{1,2,3\}$, they don't show up in the preview. See the following screen shot.

enter image description here

I tried all the different Math Renderer options, and disabling Fast Preview, with the same results.

This affects the main MO site, but not Meta.MO (so don't try to test it on this post).

When I submit the post, the braces show up correctly. Likewise, existing posts seem to render fine, but if I try to edit them, I don't see braces in the preview.

Typing $\\{1,2,3\\}$ makes the braces appear in the preview, but I expect this would mess up the output in the actual post.

I'm pretty sure this just started recently, as I think I would have noticed it before.

I can reproduce this with Firefox 42.0 on Ubuntu and Safari 9.0 on iOS (using the Full Site).

  • 2
    $\begingroup$ Same here; also on Firefox on Android. $\endgroup$
    – Asaf Karagila Mod
    Nov 22, 2015 at 18:22
  • $\begingroup$ I never got braces to work. I use \lbrace and \rbrace $\endgroup$ Nov 22, 2015 at 22:19
  • $\begingroup$ Same on chrome 46.0x on mac $\endgroup$ Nov 22, 2015 at 23:39
  • 1
    $\begingroup$ Another problem that seems very related ("not enough escaping"). A wild guess where this comes from: the citation helper Based on nothing but the problem ought to be recent and this being a recent changed. And the problem being only present on MO, at least not on math.se and matheducators.se, (neither having the citation helper). $\endgroup$
    – user9072
    Nov 23, 2015 at 18:26
  • $\begingroup$ I am seeing this behavior again, at least sporadically. Is anyone else? $\endgroup$ Aug 25, 2020 at 19:01

1 Answer 1


This had to do with the citation helper script - mostly with how I implemented the integration with the editor.

The fix is being deployed right now.

  • $\begingroup$ Yes, I can confirm it is fixed. Thanks! $\endgroup$ Nov 23, 2015 at 23:25
  • 1
    $\begingroup$ I still see this in 2023, both on mathoverflow and on math.stackexchange: \{ and \}are not rendered, and \|is rendered as a single |, not as two vert's. $\endgroup$ Sep 24, 2023 at 16:28
  • $\begingroup$ Same here, 31 Dec 2023. $\endgroup$
    – Bedovlat
    Dec 31, 2023 at 14:56

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