# What happened to this question's commutative diagram?

An old answer of mine was written, in March 2014, with a commutative diagram,

$$\require{AMScd} \begin{CD} V @>{T}>> W\\ @V{\sigma_V}VV @VV{\sigma_W}V \\ V^* @<<{T^*}< W^* \end{CD}$$


which looks like this

and which on meta renders correctly (at present) as

$$\require{AMScd} \begin{CD} V @>{T}>> W\\ @V{\sigma_V}VV @VV{\sigma_W}V \\ V^* @<<{T^*}< W^* \end{CD}$$

However, I noticed recently that the diagram was missing from the answer on main, and indeed if I try to add that code to a new question on main I get a [Math Processing Error]:

Can somebody explain what's going on? It looks pretty buggy to me.

This is a bug in the CommonHTML output for mathJax; see issue 1691 for details. You probably are using HTML-CSS output here, but CommonHTML on the main site, which is why it works here for you but not there.

• Huh, go figure, it actually does have different renderers in the two domains. Is there a way to change the TeX such that it will display correctly everywhere? The link suggests fiddling with the spaces but that doesn't seem to work, and I'm not sure what it means by 'escaping the <'. Feb 16 '17 at 18:12
• If it can be ensured to work correctly across the board, then I can change it back to the TeX. Otherwise, the current image version is probably a better idea. Feb 16 '17 at 18:13
• Also, how did you find this thread so fast? Have you got a script that monitors the bug+mathjax combination across all SE metas? Feb 16 '17 at 18:14
• There is no current workaround. The thing about quoting < is incorrect. Yes, I have a MathJax filter subscription so that I get posted about message tagged with MathJax. Feb 16 '17 at 22:02
• Ok, thanks. I'll leave it as an image until it gets fixed, then. Thanks very much for the insanely quick reply, and more generally for making MathJax the amazing piece of infrastructure that it is. Feb 16 '17 at 22:32
• Thanks for your kind words about my response and about MathJax. I'm always touched by the comments from appreciate users like yourself. Feb 17 '17 at 1:14