Proving Cyclic Extension of Finite Galois Group L/F

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SUMMARY

The discussion centers on proving that a finite extension L/F is a finite Galois extension with a cyclic Galois group Gal(L/F). The key elements include the field K, its algebraic closure K', and the automorphism sigma that defines the fix field F. The participant attempted to relate the problem to the prime subfield of F, which is either isomorphic to F_p or Q, but struggled to establish the cyclic nature of the Galois group.

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Homework Statement


Let K be a field, and let K' be an algebraic closure of K. Let sigma be
an automorphism of K' over K, and let F be the fix field of sigma. Let L/F
be any finite extension of F.


Homework Equations



Show that L/F is a finite Galois extension whose
Galois group Gal(L/F) is cyclic.

The Attempt at a Solution

 
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I thought about the prime subfiled of F, which is isomorphic to F_p or Q, and tried to prove that L is finite Galois over this prime subfield. (but failed) if I could show this, then it's obvious that L is finite galois over F since F is an intermediate field.

But for the cylic galois group, I still haven't got any idea.
 

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