# Unsolved Problem asked as a question in math.se

What are the guidelines? Will the moderators take action OR does someone have to flag it as "Known Unsolved Problem" or "Known Open Problem".

For instance question here was about a Diophantine Equation that is listed as Unsolved.

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That is one reason I go about asking people posting number-theory related questions for the source of the problem... –  Aryabhata Mar 25 '12 at 19:57
There also is the open-problem tag. –  Martin Sleziak Mar 26 '12 at 14:16

I think that an answer explaining that this is an open problem and perhaps listing a few sources for that (and maybe conjectures on the possible answers) should be a good step, no need to alert the moderators.

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I wonder if we're talking about a situation where OP knows it's a known unsolved problem and withholds that information. I could see where the moderators might want to know about such behavior. –  Gerry Myerson Mar 26 '12 at 0:58
@Gerry: yes, and it would be ironic if we can get a new closure reason "closed as 'known open problem'". –  Willie Wong Mar 26 '12 at 8:15
I can imagine the topologists saying, "Sure, a question can be simultaneously open and closed, what's the problem?" –  Rahul Mar 26 '12 at 10:23
@RahulNarain: Let $\alpha<\omega_1$ can we find a question which is $\Sigma^0_\alpha$ but not $\Sigma^0_\beta$ for all $\beta<\alpha$? –  Asaf Karagila Mar 26 '12 at 10:32
@RahulNarain Your last comment was hilarious, even if it is incorrect. :-) –  Hardy Apr 2 '12 at 8:20