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Timeline for Direct proof of irrationality?

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May 23, 2022 at 13:20 history edited Bill Dubuque CC BY-SA 4.0
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Jul 16, 2010 at 17:22 history edited Bill Dubuque CC BY-SA 2.5
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Jul 15, 2010 at 22:39 comment added Bill Dubuque Yes, of course there are many variations. But they are all mechanically derivable from the more conceptual ideal-based proofs, as I explain at length in the sci.math linked indirectly above. Thus they're all essentially equivalent and the key idea goes way back to Dedekind. I could easily write a program that could generate all of the known "elementary" proofs by unwinding the conceptual proofs, eliminating higher-order concepts like ideals, modules, and directly inlining lemmas, etc. Such elementary proofs are not novel in any way.
Jul 15, 2010 at 16:47 comment added Bill Dubuque But every proof does the same at some point - even if it's far down the line in some chain of lemmas, e.g. see the Gower's link above.
Jul 15, 2010 at 16:34 comment added Rasmus Your theorem is neat, though.
Jul 15, 2010 at 16:31 comment added Rasmus So your proof of irrationality of $\sqrt{2}$ is follows: Assume $\sqrt{2}$ was rational. Then my theorem implies that $\sqrt{2}$ is integral, which is obviously impossible since no integer squares to $2$. QED. But this is a proof by contradiction isn't it?
Jul 15, 2010 at 16:16 history edited Bill Dubuque CC BY-SA 2.5
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Jul 15, 2010 at 16:01 history edited Bill Dubuque CC BY-SA 2.5
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Jul 15, 2010 at 15:57 comment added RubeRad That's really slick too; I'll have to make some time to read the link...
Jul 15, 2010 at 15:57 vote accept RubeRad
Jul 15, 2010 at 15:45 history edited Bill Dubuque CC BY-SA 2.5
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Jul 15, 2010 at 15:34 history answered Bill Dubuque CC BY-SA 2.5