I asked a question a couple of years ago on MathStackexchange which was quite popular. I would like to ask it on MathOverflow as well, since I'd be interested in the answers there. But I'm never sure how the cross-posting rules work.

I understand that lots of overflow users still see stackexchange anyway, particularly if it was a quite popular question, but I still feel there'd be a decent portion who can provide new answers.

The question is quite subjective, since essentially I'm just asking for an example that personally satisfies me, so the question of "whether it has an answer already" is a bit difficult. In any case, I feel I don't have an answer.

  • $\begingroup$ Was it this question? $\endgroup$ Commented Jan 14, 2022 at 14:31
  • $\begingroup$ yep. (i have my answer now thoguh) $\endgroup$
    – tomos
    Commented Jan 14, 2022 at 14:35
  • 1
    $\begingroup$ Thanks, I thought I'll just put it here so that if others could access it. I don't know enough about MO to know how it would be received here, but it was well-received on MSE because the breadth offered by the question wasn't enough for closure (maybe) but was definitely large enough for many posters to have a good go at it. This question is better suited for MSE than MO in my opinion, although at MO you may get more sophisticated answers. I've voted up your question there : if you need additional attention on MSE, consider placing a bounty with a message. $\endgroup$ Commented Jan 14, 2022 at 14:39
  • $\begingroup$ no no, it was well-received on MSE and i was happy with the answers. i was just curious as to what MO users might also say (but curious enough so to really want to post it) $\endgroup$
    – tomos
    Commented Jan 14, 2022 at 17:37
  • 1
    $\begingroup$ Thanks for the response. $\endgroup$ Commented Jan 14, 2022 at 18:15

1 Answer 1


In general, cross-posting is frowned upon. And rightly so, it feels like an unnecessary duplication of effort, especially when the two communities intersect on a non-trivial subset of their users. To me, personally, this sort of behaviour feels often like a blatant disregard to the efforts of those who interact with the question.

Nevertheless, there are reasons to cross-post. One of them is that you are interested in the answers that might arise from a different context and a different community. So here is what I suggest.

  1. First of all, look closely at the people who have answered your question already. Are they members of MathOverflow? If so, there's no real reason to expect them to post a new answer, is there? (Maybe there is a reason to expect that, in which case, great.)

  2. Include links to the other question, and edit the other question to include a link over here, or at the very least add a comment, to let people know that this question also have relevant answers elsewhere.

  3. Be very explicit about what answers you've already received, and what sort of new approach you're hoping to find. In other words, why are you cross-posting? What's missing, and what new information you're trying to gain from this effort in duplication.

  4. Do not be disappointed if users still feel that this was a misguided idea, downvote, close, or delete your question.

Good luck.

  • $\begingroup$ thanks for your answer. 1 - i'll look. but i disagree with the second part - i would like to hear insight of many active overflow users who (i'd guess) would have an opinion on it, but who i just don't know if they've seen the question. 2 - of course. 3 - sure. 4 - ok:) from this, i feel i'd be allowed to cross-post (once i've addressed 2 and 3). so ye, i guess i'll try it. thanks again:) $\endgroup$
    – tomos
    Commented Jan 11, 2022 at 14:43
  • $\begingroup$ ("i disagree with the second part" - i guess i missed the bit where you then said "maybe there is...") $\endgroup$
    – tomos
    Commented Jan 12, 2022 at 10:04

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