This thing splits if we adjoin e^ipi/4.(adsbygoogle = window.adsbygoogle || []).push({});

Let [tex]\zeta[/tex]=e^ipi/4 =[tex]\frac{\sqrt{2}}{2}[/tex]+[tex]\frac{i\sqrt{2}}{2}[/tex]

so x^{4}+1=

(x-[tex]\zeta[/tex])(x-[tex]\zeta[/tex]^{2})(x-[tex]\zeta[/tex]^{3})(x-[tex]\zeta[/tex]^{4}).

Then I want to permute these roots so the Galois group is just S_{4}.

But, Q([tex]\zeta[/tex])=Q(i,[tex]\sqrt{2}[/tex]) and [Q(i,[tex]\sqrt{2}[/tex]):Q]=4 (degree)

I have the theorem that Galois group [tex]\leq[/tex] degree of splitting field over base field.

Since |S_{4}|=24 something is wrong, but what I can not find what is wrong with the logic.

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# The galois group of x^4 + 1 over Q

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