This question made me wonder if an open problem had ever been solved via collaboration on StackExchange.

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    $\begingroup$ Yes. There are some papers (and at least one masters thesis) which started as MSE questions/answers. $\endgroup$
    – Asaf Karagila Mod
    Oct 10, 2014 at 1:13
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    $\begingroup$ See the thread Papers that originated on math.SE $\endgroup$ Oct 10, 2014 at 2:13
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    $\begingroup$ Similar topic at MO: Best of MathOverflow $\endgroup$ Oct 10, 2014 at 5:39
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    $\begingroup$ Not solved, don't know if open problem. But many of us wonder. About this one. $\endgroup$
    – leo
    Oct 15, 2014 at 15:13
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    $\begingroup$ One user gave a seemingly new proof of the irrationality of root two; not an open problem of course, but original: math.stackexchange.com/questions/917983/…. $\endgroup$
    – user117644
    Oct 20, 2014 at 10:00
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    $\begingroup$ @mistermarko That is not a new proof. $\endgroup$
    – MJD
    Oct 20, 2014 at 12:03
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    $\begingroup$ You really need to provide a link to an earlier instance of it then. He genuinely thought it was new and no one could correct him. $\endgroup$
    – user117644
    Oct 21, 2014 at 5:40

1 Answer 1


Ian Wanless gave an example of a pair of orthogonal complete Latin squares of order 12 here.

The existence question was posed as a problem by Keedwell in "Some problems concerning complete Latin squares" (1974).


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