Apparently, the Stacks project can load a MathJax extension called xypic.js (check the source code) and then has access to \xymatrix in their MathJax-$\LaTeX$ code. Would it be possible to add this to MO? Diagrams are always quite difficult to do when you can only use matrix environments.

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    $\begingroup$ You might be interested in the comments to this discussion and in that discussion. (As a footnote, Davide Cervone is one of the developers of MathJax). $\endgroup$
    – Asaf Karagila Mod
    Commented Oct 8, 2013 at 14:10
  • $\begingroup$ When I checked (which was a while ago) there were still some major unresolved issues. I pinged MathJax developers for their input on the stability and security of xypic.js. $\endgroup$ Commented Oct 8, 2013 at 14:14
  • $\begingroup$ I marked the request as status-declined but we can revisit the issue if the XyJax developers offer a support plan which is suitable for our needs. $\endgroup$ Commented Oct 8, 2013 at 15:02
  • $\begingroup$ @François, you can also use status-deferred. $\endgroup$
    – Kaveh
    Commented Oct 8, 2013 at 20:45
  • $\begingroup$ I've retagged as deferred. Clearly this is something we'd like to be able to do, but xypic.js may not be ready for prime-time yet. $\endgroup$ Commented Oct 8, 2013 at 22:13
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    $\begingroup$ I reverted to status-declined since there is no plan to implement this. The XyJax developers are, as far as we can tell, nowhere near providing the support we need to deploy on MathOverflow. Of course, we would be happy to revise this if the XyJax developers come up with a suitable support plan. $\endgroup$ Commented Oct 9, 2013 at 4:49
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    $\begingroup$ To add a bit of context, a while back the main MathJax library had a quite severe security hole, which fortunately was fixed before anyone exploited it. That history makes us pretty wary of XyJax, particularly because no one has had any useful communication with the developer. $\endgroup$ Commented Oct 9, 2013 at 10:45
  • $\begingroup$ @ScottMorrison: Alright, that actually does explain the wariness. It's still a shame, diagram support would be very much appreciated I think. $\endgroup$ Commented Oct 9, 2013 at 14:57
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    $\begingroup$ To add to what Scott said, the reason we have to be more wary than the Stacks project is that random people on the internet can immediately post on MO, whereas submissions to the Stacks project are reviewed by a human before they're incorporated. $\endgroup$ Commented Oct 9, 2013 at 17:22

1 Answer 1


It appears that XyJax is developed independently from MathJax. As a result, MathJax will not support nor test XyJax. This makes integration into MathOverflow difficult since we need to have reliable support for new features. We cannot implement such features without a suitable support plan from the XyJax developers.


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