I have noticed just now that a user has chosen as pseudonym "Alexander Grothendieck", which I'm a bit unconfortable with (the probability that it is also that user's name is extremely low, hence my surmising this is a pseudonym ; apologies if it isn't.)

what is the policy of MO regarding the use of somebody else's real name as a pseudonym in general, and of a mathematician in particular ?

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    $\begingroup$ Related Celebrity usernames; in particular Todd Trimble's answer there briefly addresses the case of using mathematician's names. $\endgroup$
    – YCor
    Nov 1, 2019 at 20:04
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    $\begingroup$ ... the given user has just changed to another username ("TPC"). $\endgroup$
    – YCor
    Nov 1, 2019 at 20:07
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    $\begingroup$ Don't do it. It is an abuse of the system. I have been impacted (not positively) by someone using my username, and others have been banned for persistent behaviour of a similar nature. Gerhard "Do Not Accept Any Substitutes" Paseman, 2019.11.01. $\endgroup$ Nov 1, 2019 at 22:31
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    $\begingroup$ Thanks to those who provided answers or comments! I shall not pick one answer since both contribute interesting thoughts. I must admit I'm still unconfortable with the use of deceased people's name as a pseudonym, in particular mathematicians (including Gauss). $\endgroup$ Nov 2, 2019 at 14:01
  • $\begingroup$ Just for the record, another example of this phenomenon may be found here. Someone posting under the pseudonym "Claude Shannon" described a result of Claude Shannon and said "I proved this in 1948." Upon being told that readers found this "tribute" to Shannon to be in poor taste, the user edited the answer accordingly. $\endgroup$ Jul 28, 2021 at 2:28

2 Answers 2


I think that it makes a difference whether there is any chance that the person using the pseudonym could be confused with a more well-known person with that name.

There are a number of users who have chosen the pseudonym "Gauss" (or something similar). Obviously, nobody is going to think that Carl Friedrich Gauss has come back from the grave to post questions on MO. I don't think that such pseudonyms are any worse than a random pseudonym.

Conversely, intentional attempts at impersonation or identity theft are obviously not okay. Even non-malicious or thoughtless use of pseudonyms that could cause confusion are IMO a bad idea and should be discouraged if not banned outright.

"Alexander Grothendieck" is a borderline case. The famous Grothendieck is no longer alive, although some people might not be aware of that because he died only five years ago. Even if there were no risk that anyone would think that the user "Alexander Grothendieck" was the Fields medalist, the use of his name might be interpreted as a disrespectful gesture. I would not recommend banning the use of such a pseudonym, but perhaps the moderators could approach the user in question and gently suggest that a different pseudonym be used. Chances are the user thought that the use of the pseudonym was either harmless or even a sign of respect, and I think that a heavy-handed over-reaction would be counter-productive.

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    $\begingroup$ Why not just implement the simple rule that the user name should either be the real name or a pseudonym which can neither be confused with a real name nor is likely to offend anyone or to spark controversy? $\endgroup$
    – Stefan Kohl Mod
    Nov 3, 2019 at 13:42
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    $\begingroup$ @StefanKohl In the past the question of whether something is likely to spark controversy has itself caused much controversy. $\endgroup$
    – Will Sawin
    Nov 3, 2019 at 14:27
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    $\begingroup$ I'm not in favor of introducing unnecessary rules. "Homer Simpson" could be confused with a real name, because there are real people with that name. The same applies to "John Doe" or "Smith" or a host of other innocuous pseudonyms. Why burden ourselves with the job of policing every username that could be confused with a real name? That seems to create more problems than it solves. $\endgroup$ Nov 3, 2019 at 20:37
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    $\begingroup$ @TimothyChow Having a rule does not mean it always needs to be enforced -- it just means that one can refer to it when there is need. -- So there would be exactly zero additional burden of 'policing', but just an additional means to resolve conflicts. $\endgroup$
    – Stefan Kohl Mod
    Nov 3, 2019 at 20:59
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    $\begingroup$ @StefanKohl : I am still not in favor of laying down Code of Conduct rules if they are not necessary. Perhaps I am unduly influenced by the current uproar surrounding the recent StackExchange Code of Conduct changes, but I think that pre-emptively laying down poorly phrased rules of behavior sets the wrong tone for the site. $\endgroup$ Nov 3, 2019 at 21:31
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    $\begingroup$ @WillSawin Clearly, this process can be iterated, and can also be defined for limit ordinals. I wonder what the smallest ordinal $\alpha$ is, such that the internet cannot generate controversy of type $\alpha$? :-) $\endgroup$ Nov 4, 2019 at 16:04

It is evidently inappropriate to use someone else's identity to post on MO (or anywhere else!).

That said, people's chosen username is a sensitive issue. If someone is legitimately known as "Alexander Grothendieck", "Carl Gauss", or "Jennifer Lopez" then they should be allowed to use that name on MO. Of course, in such cases, the user in question should perhaps choose to clarify the potential confusion. While we strongly encourage this, there is no requirement to do so for the same reason that I never have the requirement to distinguish myself from all the "François Dorais" that exist. (Even though my name is not common, an easy search reveals plenty of other people with my name.)

When suspicion of an illegitimate name use arises, the MO moderators and SE staff can investigate further. In the event of misappropriation, then actions will be taken to clarify authorship.

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    $\begingroup$ I support that it is wrong to use as username the real names of other person. I don't understand why a person would want to use the name of a famous person, in particular, a famous/well-known mathematician. I think it is wrong to use the name of famous mathematicians, contemporary or not, men or women. $\endgroup$
    – user142929
    Nov 2, 2019 at 8:32
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    $\begingroup$ @user do you understand why a couple might want to name their child after some famous person for whom they have respect and admiration? People do that all the time. How different is taking a username of a famous person one respects and admires? $\endgroup$ Nov 2, 2019 at 11:24
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    $\begingroup$ What I can say is that I respect him, @GerryMyerson . And for me the theories of this mathematician are inaccessible, but that is not the point $\endgroup$
    – user142929
    Nov 2, 2019 at 11:28
  • $\begingroup$ Now I know how you form the plural of "François Dorais". :-) $\endgroup$
    – LSpice
    Nov 2, 2019 at 14:43
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    $\begingroup$ On a side note, the choice of those three names in the example may be considered as repeating a gender stereotype.... :) $\endgroup$ Nov 3, 2019 at 7:19
  • $\begingroup$ @PietroMajer, you mean the stereotype that all non-mathematicians are women? ;-) $\endgroup$ Nov 7, 2019 at 10:59
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    $\begingroup$ :) The stereotype that the natural way for a woman to became famous is dancing and singing, while the natural way for a man is doing science. My comment was semi-serious, because I'm 100% sure the OP had no intention of gender discrimination, and because I know sometimes these issues may be exaggerated. Yet these problems do exist, and I think we should always be careful, also in naives examples, because the assumptions they carry have some influence on the way people think. $\endgroup$ Nov 7, 2019 at 11:36
  • $\begingroup$ I believe that there is risk about if some person read the answers/comments in the future maybe they will think that some people were exaggerated or we were overreacting here, it is not so at least in my case, because I knew the profile of the mentioned user in this MathOverflow in several of those posts, and comments of users reacting to this situation. I shut up by then, but from what I saw I'm not exaggerating. $\endgroup$
    – user142929
    Nov 9, 2019 at 13:10
  • $\begingroup$ I think that if in future someone edit posts in this site with the name and surname and/or photo of a mathematician died few years ago, it should be considered for the moderators and this community of users as a problem @GerryMyerson $\endgroup$
    – user142929
    Mar 12, 2020 at 8:24

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