# Preserve or remove formula formatting in the question title?

This question uses $\mathrm{CO}_2$ formatting in the title (Latex I believe MathJax).

Picture in case someone edits it out:

Personally I find it superfluous and annoying - you see the title being constructed (4 'jumps'!) in the browser when you visit any page displaying that title.

But in running texts (on other SE sites as well) chemical formulas are often written this way, because if offers the possibility of subscripts.

Should we edit and remove this kind of formatting in titles?

Here is a meta.SE question about backticks in the title where the answer states Markdown isn't run on the title whatsoever. Any special characters get converted to their entities. This suggests that any formatting should be avoided.

• Note that the $...$ and $$...$$ is mathjax, not markdown. Mathjax gets parsed client side by a javascript library included in the page. They do render in titles except on mobile, where you'll see the raw mathjax markup. – casey Sep 1 '15 at 13:43
• @casey That would be an argument for removing the formatting – Jan Doggen Sep 1 '15 at 14:47
• To note: this is not a major issue, but if a question title contains mathjax, it will not be shown in the Hot Network Questions. Other than that, I'm not aware of any issues -- simply personal preference. – hichris123 Sep 3 '15 at 1:32

The $...$ and $$...$$ are not markdown but rather mathjax, which is parsed clientside by a javascript library when you load the page. This will render in titles and comments except on mobile, which only runs mathjax on post content.

For simple to recognize content, I think mathjax is fine in titles. I might prefer $\ce{CO2}$ ($\ce{CO2}$) over $\mathrm{CO}_2$ ($\mathrm{CO}_2$) and definitely over $CO_2$ ($CO_2$).

The downside to mathjax in titles is that they are not universally rendered (e.g. on the Android SE app) and they are stripped from google:

But this doesn't really pose problems in searching unless your title is completely mathjax and there is not much going on in your post. This might be an issue for the math stack exchanges, but not really for us.

There are various debates on the use of unicode vs mathjax for subscript/superscripts in titles, and that comes down to preference. I wouldn't go around editing one to the other.

Related:

• If mhchem is supported here that should be added to the list at meta.stackexchange.com/a/216607/189029 – Jan Doggen Sep 1 '15 at 19:56
• @JanDoggen feel free to edit that post to include it. It isn't an authoritative list. The easiest way to check is to just try to use them in a post (you don't have to actually submit the post, they'll render in the preview if they are turned on) – casey Sep 1 '15 at 19:58
• An additional (minor) limitation is that such questions can not end up in the Hot Network Questions list, as titles containing mathjax are filtered out since they are not rendered on all SE sites. – plannapus Sep 2 '15 at 6:23