# About a past question [closed]

In What is the center of a semidirect product?, Alexander Gruber answered a question of user39794. Is there cited reference for this? I want to cite this result. Is it given in some book or paper? Kindly tell me the reference for that.

## closed as off-topic by Did, Nick Peterson, azimut, Adriano, JaredAug 29 '13 at 23:13

• This question does not appear to be about math within the scope defined in the help center.
If this question can be reworded to fit the rules in the help center, please edit the question.

• You should ask this as a comment on the original question.... – Simon Hayward Aug 29 '13 at 13:14
• This question should be asked as a comment on the question the OP references. – Nick Peterson Aug 29 '13 at 21:42
• @ Simon Hayward, @ Nicholas R. Peterson To comment on other question I need 50 reputation score which I do not have. Therefore I asked this as new question. – Jacob Aug 30 '13 at 4:52

I dunno if it's anywhere in the literature, I just derived it. If you want, you can cite the MSE post using this BibTeX code

@MISC {243412,
TITLE = {What is the center of a semidirect product, $\operatorname{Z}(G_1 \rtimes_\varphi G_2)$?},
AUTHOR = {Alexander Gruber (http://math.stackexchange.com/users/12952/alexander-gruber)},
HOWPUBLISHED = {Mathematics Stack Exchange},
NOTE = {URL:http://math.stackexchange.com/q/243412 (version: 2013-06-02)},
EPRINT = {http://math.stackexchange.com/q/243412},
URL = {http://math.stackexchange.com/q/243412}
}


which I got from using MSE's built in citation thingamajig, as described by WillieWong here.

If you don't want to do that, I doubt it'd be in any papers, but you could look around in semidirect product sections in Dummit and Foote or Artin and see if it occurs as a problem somewhere.

• Why answering a question which should have been asked as a comment on the original question? – Did Aug 29 '13 at 21:26
• Knew the answer – Alexander Gruber Aug 30 '13 at 5:31
• Not sufficient. – Did Sep 5 '13 at 9:32
• Sorry but this won't do: to say that one answers any question just because one "knew the answer" is to deliberately flout the fact that MSE has a well defined, restricted, scope, which, by pure logic, implies that some questions are out of this scope. (Incidentally, the tone of your two comments is most peculiar.) – Did Sep 5 '13 at 15:37
• To adopt a condescending tone (which you acknowledge) instead of addressing at the onset the specific and restricted point I raised is a choice you can make. Allow me to disagree. – Did Sep 6 '13 at 7:46