Galois extension, lattice of subfields

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SUMMARY

The discussion centers on the Galois extension \( K = \mathbb{Q}(\sqrt{2+\sqrt{2}}) \) over \( \mathbb{Q} \). It is established that the Galois group \( \text{Gal}(K/\mathbb{Q}) \) is isomorphic to \( \mathbb{Z}_4 \). The participants seek assistance in accurately constructing the lattice of subfields, which is directly related to the lattice of subgroups of the Galois group.

PREREQUISITES
  • Understanding of Galois theory and extensions
  • Familiarity with the structure of Galois groups, specifically \( \mathbb{Z}_4 \)
  • Knowledge of field theory and subfields
  • Ability to visualize and construct lattices
NEXT STEPS
  • Research the properties of Galois groups, focusing on \( \mathbb{Z}_4 \)
  • Learn how to construct and interpret the lattice of subfields in Galois theory
  • Study examples of Galois extensions and their corresponding subfield lattices
  • Explore the relationship between Galois groups and subgroup lattices
USEFUL FOR

Mathematicians, particularly those specializing in abstract algebra, field theory, and Galois theory, will benefit from this discussion.

mathsss2
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K=\mathbb{Q}(\sqrt{2+\sqrt{2}}) is a Galois extension of \mathbb{Q} [I showed this]. Determine \text{Gal}(K/\mathbb{Q}) and describe the lattice of subfields \mathbb{Q} \subset F \subset K.

I found that \text{Gal}(K/\mathbb{Q})=\mathbb{Z}_4. I do not know how to draw the lattice of subfields, so far I have this: [see attachment], but I do not think it is right. I need help with the lattice of subfields.
 

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Recall that the lattice of subfields is directly correlated to the lattice of subgroups of the galois group. This should make it easier
 

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