# Of which question is this question duplicate?

This question "Direct proof that $\sqrt{2}$ is irrational?" is marked as duplicate. In other duplicate questions, there is a link to the original question but not in this question.

So where is the original question?

If you have a look at revision history, you will see that a user removed the following part of the post (the duplicate banner):

Possible Duplicate:
Irrationality proofs not by contradiction

You can see the same post mentioned in the comments and among the linked questions on the right.

EDIT: As explained, for example, in the answers to this Why can I edit out the Possible Duplicate Banner from this question?, the duplicate banner used to be edited in by the community bot, in which case it is basically the normal text. It also says that this behavior was changed in February 2013, so question that were marked as duplicates later should not contain the banner directly in the post. See also Should users be allowed to remove the "Possible Duplicate" links on closed questions?

• I wasn't aware of the fact that one can edit the duplicate banner. – user103816 Nov 11 '14 at 8:25
• @user31782 I might be wrong, but I think that it is not possible anymore. (Notice that this was a rather old post.) – Martin Sleziak Nov 11 '14 at 8:26
• And even if this is still possible, I think it is a very bad thing to do. (But I did not edit the post, I will wait whether some of the mods will or more experienced users will chime in). – Martin Sleziak Nov 11 '14 at 8:30
• Perhaps there was some bug, which might have been fixed now. – user103816 Nov 11 '14 at 8:39