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 ...


The user has changed to another username Math is like Friday. (Just answering to make the possibility of considering the issue as solved.)


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 ...


The answer that I found that works for me is backslash semicolon \; I found this answer at https://texblog.org/2014/04/09/whitespace-in-math-mode/

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