I'm editing Is there a canonical map from the cohomology of orbifold Chiral de Rham on an orbifold to the cohomology of Chiral de Rham on a crepant resolution? as there was a broken arXiv Front link (and I took the opportunity to add some paper titles in). But I cannot submit the edit as the question title is 'Too long by 1 character'. I have a vague memory of this issue coming up before, but I cannot find it here on meta. Obviously I could shorten the title (say by making it as "A canonical map....resolution?"), but this does change the sense slightly.

Here's a screenshot:

screenshot of title "Too long..." warning

What should be our practice here? And I'm leaning towards calling this slightly buggy behaviour hanging over from the transition from SE1.0 to SE2.0, though I know it's operating as intended. Presumably this came up long ago on other sites, if it's a SE1.0 -> 2.0 issue?

I have saved a local copy of the new source text of the question, but have left it open for editing, in case there's a quick answer. If not, I'll cancel the edit, and paste in the updated source later, once there's consensus on how to proceed.

Edit: title has been tweaked, but I think discussion needs to be had around this, or else the old discussion found and linked to.

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    $\begingroup$ Replace "between" with "from" and "and" with "to" and you're golden. $\endgroup$
    – Asaf Karagila Mod
    Commented Mar 18, 2022 at 0:09
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    $\begingroup$ Sure, but what if it were too long to play a simple trick like that? Looking for discussion around policy here. What was the old character count? How bad could it get? $\endgroup$
    – David Roberts Mod
    Commented Mar 18, 2022 at 0:12
  • $\begingroup$ I've done the question edit, with your title suggestion @Asaf, but the point still stands. $\endgroup$
    – David Roberts Mod
    Commented Mar 18, 2022 at 0:13
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    $\begingroup$ Another post concerning the same issue: Unfortunate title length limitation when performing dead link maintenance. $\endgroup$ Commented Mar 18, 2022 at 3:57
  • $\begingroup$ @MartinSleziak thanks for that. Do we know any of the reasons behind how this difficulty arises? $\endgroup$
    – David Roberts Mod
    Commented Mar 18, 2022 at 6:15
  • $\begingroup$ @DavidRoberts Well, as you said yourself, the only reasonable explanation is that the limit used to be longer. I did not find exactly when it was changed, but in 2015 it was already at 150: Edit to an old question cannot be saved because title too long, (Maybe you'll have better luck in finding some info on this change.) SEDE returns 126 posts with titles longer than 150 characters: data.stackexchange.com/mathoverflow/query/1568947/… Here are results of the query from the linked post... $\endgroup$ Commented Mar 18, 2022 at 6:25
  • $\begingroup$ ... data.stackexchange.com/mathoverflow/query/363314. Maybe in this context it is also worth reminding what is the recommendation from here: How to write a good MathOverflow question?: "Titles are allowed to be anywhere from 15 to 150 characters long. 140 characters (the length of a tweet) takes up about two full lines on the home page, so try to keep it less than that." (See the link to read the whole advice on titles as stated in the post - I have included only a brief excerpt.) $\endgroup$ Commented Mar 18, 2022 at 6:27
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    $\begingroup$ @Martin The last >150 char question was on the 13th June 2013 (there were usually only a handful a month and there were two in that June), and it seems MathOverflow 1.0 was turned off on the 24th (see last post). So it's very likely a 1.0->2.0 effect. $\endgroup$
    – David Roberts Mod
    Commented Mar 18, 2022 at 8:21
  • $\begingroup$ Actually "cohomology of orbifold chiral de Rham on an orbifold" sounds so clumsy that I don't see what exactly "chiral de Rham" refers to. $\endgroup$
    – YCor
    Commented Mar 18, 2022 at 9:26
  • $\begingroup$ @David: Absolutely, that's why I posted a comment not an answer. $\endgroup$
    – Asaf Karagila Mod
    Commented Mar 18, 2022 at 12:21
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    $\begingroup$ Here is an answer explaining the reduction from 250 to 150 characters. $\endgroup$
    – Glorfindel
    Commented Mar 29, 2022 at 19:59

1 Answer 1


In the end, the title could be rephrased just slightly to get in under the limit. But in the future, I guess it would be suitable to summarise titles that are too long on posts that need editing, but then record the original title at the top of the body of the question. There was a post on meta.SE explaining the rationale behind the shorter character limit, mostly because long titles really messed with the page layout, and not a terrible move as the relatively few questions that really pushed the old (250 character) limit were generally really poorly titled.

When MO moved onto the SE2.0 platform, we accepted the limitations (as it were) of the software. The date at which >150 char titles stopped being possible doesn't line up with when the software changed for SE as a whole (first half of 2010), since this is when it came into effect for us. The last >150 char question title was on the 13th June 2013 (there were usually only a handful a month and there were two in that June), and it seems MathOverflow 1.0 was turned off on the 24th June 2013.


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