# Broken math on some answers [duplicate]

Here is an example. Is there an automatic way for moderators to fix what I imagine are many answers that somehow now display funny, or should we do it manually, one by one?

If the latter, people could use this question to list the answers that need attention (if they rather don't edit them themselves).

• – Joel Reyes Noche Jun 25 '13 at 4:55
• In this answer it seems the math crosses over the text mathoverflow.net/questions/20960/… – Anixx Jun 25 '13 at 5:06
• I have come across several broken posts, partly due to the use of backticks. However, here is a question which seems to be completely broken, but has no backticks: mathoverflow.net/questions/70419/unbased-spectral-sequences. Interestingly, when you try to edit the question, it renders fine in the preview. – Ricardo Andrade Jun 26 '13 at 2:29
• @RicardoAndrade, I fixed that one. Put {} around subscripts. – Fred Kline Jun 26 '13 at 19:09

I suspect if we can concoct some regular expressions that catch common sources of LaTeX problems we may be able to get some automatic replacements run on the database.

I'm guessing this is our back-ticking habit coming back to haunt us, now that the interaction of markdown and MathJax has changed slightly.

• Ah, that must be, of course! I'll wait then before going through hundreds of answers, despairing, and trying to edit them one-by-one by hand. – Andrés E. Caicedo Jun 25 '13 at 5:04
• I have removed a majority of the backticks that exists in posts. If you do fine a pattern in the anomalies I'll be happy to fix them up without you having to do any work. – Geoff Dalgas Jun 25 '13 at 19:27
• Thanks, @GeoffDalgas ! – Andrés E. Caicedo Jun 26 '13 at 0:39

My post at Symmetric subspace of linear operators is broken. Worse yet, I am unable to fix it because (apparently) backticking formulae just makes their LaTeX code verbatim rather than disabling markup. When I try to edit my post, the preview loads fine, but the post itself doesn't!!

• I have fixed your post by adding whitespace at the bottom of the post and saving. I'll look at why this happened. – Geoff Dalgas Jun 25 '13 at 19:37
• To follow up - backticks are no longer required for mathjax formulas. – Geoff Dalgas Jun 25 '13 at 19:38
• Oh! Was the markup being cached? – darij grinberg Jun 25 '13 at 20:03
• @GeoffDalgas OK, it seems that a lot of \{ \} in between $signs have been replaced with { } and are therefore invisible when compiled. For example, here (the display formula for$\Delta_2$), and here (the definition of$\mathbb T$). – Andrés E. Caicedo Jun 26 '13 at 0:50 • @Geoff: Any update on the white space situation, and why the posts look fine in the previews, but then render incorrectly? – Ricardo Andrade Jun 26 '13 at 2:37 • I'm failing to see what you mean - here is what I see: i.stack.imgur.com/wy5Lb.png – Geoff Dalgas Jun 26 '13 at 2:55 • @GeoffDalgas Compare line 3 in the actual post (left) with line 3 in the preview (right). After the$\mathbb T=$on the left there is a$z$, while on the preview on the right there is a$\{z$. Same with the$\}\$: It appears on the preview and not on the actual post. (Strange, though: I was sure when I looked at the source earlier, there was only { rather than \{, etc, and I reported accordingly. It appears I was mistaken. Sorry about the confusion.) – Andrés E. Caicedo Jun 26 '13 at 7:11

Two of my questions (1, 2) are not displaying properly, but they were before the upgrade. Furthermore, when I go to edit the posts, they display correctly.

• I fixed 2 and 1 is pending peer review. I put {} around the subscripts. – Fred Kline Jun 26 '13 at 19:21
• Thank you very much. I think the answer to the second question needs an edit as well. – Michael Albanese Jun 27 '13 at 3:20
• Fixed the array syntax in the answer. Changed \\ to \cr. – Fred Kline Jun 27 '13 at 4:11