The following thirteen(!) users:
(and, I believe, a couple more besides) have the following characteristics in common:
- They've all joined in the past few days.
- Each has asked exactly one question
- Their questions are closely related to each other
- Their writing styles are very similar
- After posting their questions, they never return to engage with commenters, or to acknowledge answers
I think it is not too much of a leap to conjecture that these are all the same person.
As far as I know, there's no actual rule against having fifteen different identities (or for that matter, a hundred, as seems likely if this keeps up at this rate for a few more weeks), and no actual rule against asking questions and then systematically ignoring responses, but I still find it troubling in ways that might or might not be entirely rational on my part. Do others share my discomfort?
Edit (YCor June 3, 2019): since the question was posted, here are a number of similar posts:
user138661 (account closed since then: not the original post name)
Gimme An Answer
Name (not the same as previous one)
(there are a few more, for which the similarity is less obvious). In addition, this June 3, 4 of these posts have been bountied by other users: cardinal, Cut the wood, kartop_man (this one and this one, and now for the time being self-deleted: https://mathoverflow.net/users/141715/kartop-man).
Edit: I'll add more as I see them. Please note that these accounts have a tendency to comment on, edit, and answer each other's questions, or plan on offering each other bounties. The evidence I see points to one human in particular behind all this, and the situation is similar to that of another user and his ring of accounts a few years ago that some of you may recall, and who is now permanently banned from SE.
New Asura Path, possibly temporary: https://mathoverflow.net/users/141752/asura-path?tab=profile
https://mathoverflow.net/users/141790/numberian (now 141790, 141792, 141793, 141794, 141795)
(YCor 2019/July/12) A last fact, of one higher level in misbehavior (if confirmed), is the use of an username that is a seemingly real name (Denis Chaperon de Lauzières), which has been a real user of MO (real accounts here and here). Two suspicious posts under 1 user with this name were posted here and here (user now removed and both question deleted by community), and a comment-like answer here (same name, other account - now converted to a comment).