For my recently asked Physics SE question How can an $n=25$ Rydberg state exist in a solid? What does the wave function look like? an edit was made changing n=25 to "$n=25$". Presumably this was seen as a necessary improvement and not just a trivial edit.

I know there has been some issues in the past with regard to MathJax in question titles and rendering issues in the HNQ sidebar, but I can not figure out the exact status of this situation in 2022.

I was under the impression that inserting MathJax into a question's title could interfere with the question getting to, and remaining in the HNQ, perhaps by design or perhaps through someone removing it for aesthetic reasons (e.g. bad rendering) but I can not find out the exact state of the situation now in 2022. So I'd like to ask:

Question: In 2022, what actually happens to a candidate question for the HNQ when MathJax is in the title? (e.g. edit changing n=25 to "$n=25$")

So far I've found the following comments:

March 12, 2019:

...the formula picks a set of questions, which we then narrow down - throw away questions picked > 3 days ago, remove questions with MathJax in titles and questions that aren't in English, then trim per-site options down to 5 hottest, and grab top 100 for HNQ out of that. Note that the list is cached (and, under normal circumstances) recalculated every 15 minutes. Any given question isn't guaranteed to spend 72 hours in the list...

March 21, 2019:

So in other words, anyone with edit permissions is able to unilaterally knock questions off of HNQ on any site that supports MathJax? That's a little silly.

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    While there are several questions about MathJax and titles, please don't suggest duplicates just because they contain those words. I've asked here "what actually happens?" and if all problems are solved and it's smooth as silk, then that's the answer! But if there are still outstanding issues in 2022, then those are the answer!
    – uhoh
    Commented Apr 15, 2022 at 23:35
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    This 2014 comment is the official explanation I see linked around most often, not sure how relevant it still is.
    – bobble
    Commented Apr 15, 2022 at 23:45
  • @bobble I see "the problem is simply that we don't want to turn on MathJax everywhere, most notably on StackOverflow, so those titles don't render correctly." thanks! Of course MathJax can be turned on page-by-page instead of an entire site, and presumably some of the page loading issues in 2014 will be viewed differently in 2022.
    – uhoh
    Commented Apr 15, 2022 at 23:49
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    @uhoh There are several comments from 2020 (so one year later than yours) to this answer of Math meta's Autofilters for Hot Network Questions. An example is this comment of "There $is$ a filter already, called MathJax. It was used, repeatedly, before the existence of the current moderator tool. I will provide you a small sample of examples tomorrow morning, if you'd like." ... Commented Apr 16, 2022 at 1:33
  • @uhoh (cont.) A second one is this comment starting with "Matt, abusing the MathJax "hack" would be just adding ${}$ to remove a question from the HNQ. ...". Both of these are by Asaf Karagila, a moderator on both the Math and MathOverflow sites. Finally, there's a third comment starting with ... Commented Apr 16, 2022 at 1:36
  • @uhoh (cont.) You insist that "the algorithm" must be allowed to decide, an algorithm that was devised by humans (by the way, do you know what it does?). These humans decided at some points that this algorithme will filter out every question from our site whose title contains the symbol $. ..." This comment is from quid, who is a moderator of the Math and Mathematics Educators SE sites. Note I have posted any of this in an answer since I'm not sure if they are official and recent enough to count as being sufficient as an answer. Commented Apr 16, 2022 at 1:39
  • @uhoh One final note is that, with that same Math meta post, the accepted answer by Catja which states "... The filter regex looks like this: (\W|^)(?i)(urgent|ASAP|please|pls|help)(\W|$) ...". My understanding of regex syntax is that this doesn't exclude titles containing any '$' characters, but I suspect Catja meant that this was to be used in addition to that exclusion. Commented Apr 16, 2022 at 1:44
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    If the moderators on Mathematics are still hard at work removing questions from HNQ, then the previous configuration that excludes questions with MathJax markup in titles from it still exists. (They've been doing so because this exclusion results in the algorithm picking low-quality questions because those are the only ones available to choose as all the good questions contain MathJax in their titles.) Commented Apr 16, 2022 at 2:38
  • Are you asking if MathJax in the title still blocks a question from the HNQ?
    – PM 2Ring
    Commented Apr 16, 2022 at 7:00
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    FWIW, on Astronomy.SE, we tend to edit unnecessary MathJax out of titles to good questions. ;)
    – PM 2Ring
    Commented Apr 16, 2022 at 7:02
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    Related: physics.meta.stackexchange.com/q/12706/123208
    – PM 2Ring
    Commented Apr 16, 2022 at 10:35

1 Answer 1


It would be good to have a staff member answering this, but I can provide some observational evidence that the rule is still in place, with the help of the Stack Exchange Data Explorer. The Hot Network Questions list is refreshed every 3 minutes, so we can check title edits which happen less than three minutes before a question becoming a Hot Network Question with this SEDE query.

When you run it on a couple of math-oriented sites, you see that some questions which were long eligible for HNQ already, only became so after the title edit. Here are some results:

Almost all questions which become HNQ do shortly after 8 hours, so this is definitely evidence that the "no MathJax in HNQ" rule is still in place.

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