Can the following question be posted? “Where could an error be in the proposed proof of Fermat Last Theorem? Info about the author, proof and preliminary validation is at (link)”. How should the question be reformulated to not be deleted? Previously, I tried to post a similar question with more details, but it was deleted.
1 Answer
That is offtopic, as is asking for correctness of claimed proofs about any famous conjecture, especially if, as I guess, it's a simple proof and the link is at viXra or ResearchGate or Google Drive/Dropbox etc. Even if it's on the arXiv, that's not going to get a free pass, since people get claimed but completely broken proofs of famous conjectures not infrequently. You should think of MathOverflow as something like a mathematics department common room. If you wouldn't barge in and start pushing a copy of your paper on everyone present asking them to check it now, then it's not suitable here. And if someone did come barging in to the common room in this way, they would be shown the door as fast as possible, which is what happens here.
Even if someone comes asking about the correctness of a random preprint they found (on Twitter or Reddit of Facebook or whatever), it's offtopic. Sometimes people come asking for such verification of their own work, but pass it off as something they just happened across, asking here under a pseudonym. Such behaviour is clearly not going to help.
There is a long history of such a policy for this and similar situations, for example:
What is our policy on asking about correctness of preprints?
Is there a clear rule against "check this proof" type questions?
"Questions" of the type "I have written something, please give me feedback"
And in case anyone thinks that this is a gatekeeping issue of the mathematics community keeping people out, see the discussion here:
https://meta.mathoverflow.net/a/3902/4177
where the matter of a preprint with a claimed proof of a famous open problem by a famous mathematician needed to be dealt with. The tl;dr is that it is still offtopic.

2$\begingroup$ This is of course a good answer, but Re the last sentence of the first paragraph: it's not suitable even if they did barge in and pushed a copy, etc. :) At least not before they had established credibility. An incredibly ingenious 3page technique that had somehow been overlooked by everyone ought to be able to handle other hard problems with impressive dispatch, and this is what every amateur wouldbe Solver of Big Problems ought to cultivate. Such amateurs could even pose challenges in the manner of 16th century mathematicians, just to demonstrate how bloody ingenious they are. $\endgroup$– Todd Trimble ModCommented Feb 7, 2022 at 3:55

3$\begingroup$ Even if the person posting is not the person who has written the alleged proof, it's still offtopic here, and has been for as long as I can remember. $\endgroup$ Commented Feb 7, 2022 at 5:11

$\begingroup$ Thanks both, I will update to clarify. $\endgroup$– David Roberts ModCommented Feb 7, 2022 at 7:16

$\begingroup$ Thank you for the helpful explanation. $\endgroup$– shesyuCommented Feb 7, 2022 at 13:08