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Timeline for $a^b=b^a$ and algebraicity [closed]

Current License: CC BY-SA 4.0

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May 19, 2019 at 21:20 history closed abx
Wojowu
YCor
Felipe Voloch
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May 19, 2019 at 20:19 comment added Sylvain JULIEN Thank you Todd for these words in my mother tongue :-)
May 19, 2019 at 20:08 comment added Todd Trimble If you say so, Wojowu. I mean, thanks for the additional explanation, but I said easier for me, and that might still be true even after your addition. Chacun a son gout, or however it goes.
May 19, 2019 at 19:56 vote accept Sylvain JULIEN
May 19, 2019 at 19:55 answer added Wojowu timeline score: 8
May 19, 2019 at 19:51 comment added Sylvain JULIEN @Wojowu : thank you for your comment. Maybe you can post it as an answer so that I can accept it.
May 19, 2019 at 19:31 comment added Wojowu @ToddTrimble I think it's actually (slightly) easier to keep the problem as stated. If $3^b=b^3$ and $b\neq 3$, it's clear that $b$ is not an integer, and hence that $b$ is irrational (as else $b^3$ is rational and $3^b$ isn't) and hence transcendental (Gelfond-Schneider). (also, it's Wojowu, not Wojuwo :) )
May 19, 2019 at 18:15 comment added Todd Trimble Picking up on Wojuwo's comment: it's easier for me to contemplate $a^{1/a} = b^{1/b}$. By Gelfond-Schneider, if $b$ is algebraic and irrational, then $b^{1/b}$ will be transcendental. So in the case $a = 3$, we would need a rational $b \neq 3$ to satisfy $b^{1/b} = 3^{1/3}$, and then it's just a matter of the fundamental theorem of arithmetic to rule out this possibility.
May 19, 2019 at 17:20 review Close votes
May 19, 2019 at 21:25
May 19, 2019 at 16:49 comment added Wojowu No, by Gelfond-Schneider. Take $a=3$ and suitable $b$ for instance.
May 19, 2019 at 16:39 history asked Sylvain JULIEN CC BY-SA 4.0