```The following thirteen(!) users:

<a href="https://mathoverflow.net/questions/330472/functors-reflecting-colimits">goingfullscheme</a>
<a href="https://mathoverflow.net/questions/330404/when-are-valuative-criteria-useful">valua_aint_no_galois</a>
<a href="https://mathoverflow.net/questions/330342/connected-components-of-open-dense-subspace">logicians_rule</a>,
<a href="https://mathoverflow.net/questions/330178/a-slightly-canonical-way-to-associate-a-scheme-to-a-noetherian-spectral-space">bundlist</a>
<a href="https://mathoverflow.net/questions/330168/compact-quasi-coherent-sheaves">compactbut</a>
<a href="https://mathoverflow.net/questions/330159/noetherian-stalks-imply-locally-noetherian">faptoint</a>
<a href="https://mathoverflow.net/questions/330000/finite-picard-group">you_dont_mess_with_ron</a>
<a href="https://mathoverflow.net/questions/329997/affine-open-with-irreducible-complement">ron_is_striking_back</a>
<a href="https://mathoverflow.net/questions/330453/algebras-such-that-the-tensor-product-with-any-noetherian-algebra-is-noetherian">Emmy_to_Noether</a>
<a href="https://mathoverflow.net/questions/330337/noetherian-and-finitely-generated-for-polynomial-algebras">commutative_drinker</a>

(and, I believe, a couple more besides) have the following characteristics in common:

<ul>
<li>They've all joined in the past few days.</li>
<li>Each has asked exactly one question</li>
<li>Their questions are closely related to each other</li>
<li>Their writing styles are very similar</li>
</ul>

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?

<hr>
Edit (YCor June 3, 2019): since the question was posted, here are a number of similar posts:

[user138661](https://mathoverflow.net/questions/330690/grothendieck-topology-on-a-scheme-equivalent-to-the-circle) (account closed since then: not the original post name)<br>
[m_for_motive](https://mathoverflow.net/questions/330766/proper-variety-containing-no-affine-open-with-irreducible-complement)<br>
[drama_dorama](https://mathoverflow.net/questions/331666/the-underlying-space-of-an-affine-open-dense-subscheme)<br>
[gentleman_gaga](https://mathoverflow.net/questions/331914/does-the-structure-morphism-matter-in-gaga)<br>
[motive_for_m](https://mathoverflow.net/questions/332103/a-different-sort-of-affinization)<br>
[livehard](https://mathoverflow.net/questions/332120/equipotent-non-homeomorphic-schemes)<br>
[user141225](https://mathoverflow.net/questions/332839/checking-universal-closedness-on-immersions)<br>
[PDShoot](https://mathoverflow.net/questions/332949/scheme-locally-of-finite-type-over-the-affinization)<br>
[La fille](https://mathoverflow.net/questions/332969/non-empty-affine-open-with-an-irreducible-complement)<br>
[Name](https://mathoverflow.net/questions/333039/strongly-abnormal-schemes)<br>
[Name](https://mathoverflow.net/questions/333008/quasi-compact-morphisms-satisfying-the-valuative-criterion-of-properness) (not the same as previous one)<br>

(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](https://mathoverflow.net/questions/332103/a-different-sort-of-affinization), [Cut the wood](https://mathoverflow.net/questions/332969/non-empty-affine-open-with-an-irreducible-complement), kartop_man ([this one](https://mathoverflow.net/questions/332949/scheme-locally-of-finite-type-over-the-affinization) and [this one](https://mathoverflow.net/questions/332969/non-empty-affine-open-with-an-irreducible-complement), 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.

https://mathoverflow.net/users/141417/etalien <br>
https://mathoverflow.net/users/141410/topo-mopo <br>
https://mathoverflow.net/users/141546/naraka-path <br>
https://mathoverflow.net/users/141523/preta-path <br>
https://mathoverflow.net/users/141501/animal-path <br>
https://mathoverflow.net/users/141500/human-path <br>
https://mathoverflow.net/users/141498/asura-path <br>
New Asura Path, possibly temporary: https://mathoverflow.net/users/141752/asura-path?tab=profile <br>
https://mathoverflow.net/users/141474/deva-path <br>
https://mathoverflow.net/users/140692/drama-dorama <br>
https://mathoverflow.net/users/141703/curious-girl <br>
https://mathoverflow.net/users/141716/phd <br>
New https://mathoverflow.net/users/141770/phd <br>
https://mathoverflow.net/users/141790/numberian (now 141790, 141792, 141793, 141794, 141795)

<hr>

(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][1] and [here][2]). Two suspicious posts under 1 user with this name were posted [here][3] and [here][4] (user now removed and both question deleted by community), and a comment-like answer [here][5] (same name, other account - now converted to a comment).

[1]: https://mathoverflow.net/users/20038/denis-chaperon-de-lauzi%C3%A8res
[2]: https://mathoverflow.net/users/57842/denis-chaperon-de-lauzi%C3%A8res