Proving that the Galois group of the cyclotomic field $\mathbb{Q}(\zeta_n)$ is isomorphic to $U(\mathbb{Z}/n\mathbb{Z})$
9129
Show that $\mathbb{Q}(\zeta_n)$ is Galois over $\mathbb{Q}$ and $Gal(\mathbb{Q}(\zeta_n)/\mathbb{Q}))\cong \mathbb{Z_n}^*$
42810
Is $(\mathbb{Q},+)$ isomorphic to $(\mathbb{Q}^n,+)$?
109596
Isomorphism from $\mathrm{Aut}(\mathbb{Z}/2\mathbb{Z}\times \mathbb{Z}/2\mathbb{Z})$ to $S_3$
155669
$\mathrm{Aut}(D_4)$ is isomorphic to $D_4$
36142
What is $\mathbb Z \oplus \mathbb Z / \langle (2,2) \rangle$ isomorphic to?
146617
A complete picture of the lattice of subfields for a cyclotomic extension over $\mathbb{Q}$.
3711
Finding the intermediate fields of $\Bbb{Q}(\zeta_7)$.
73713
Prove that $\mathbb{Q}(\sqrt{(2+\sqrt{2})(3+\sqrt{3})})$ is Galois over $\mathbb{Q}$ is Galois and determine the Galois group
42153
Every finite abelian group is the Galois group of some finite extension of the rationals
31216
Is the image of $\Phi_n(x) \in \mathbb{Z}[x]$ in $\mathbb{F}_q[x]$ still a cyclotomic polynomial?
12524
Galois group of $x^3 - 2 $ over $\mathbb Q$
32302
Neukirch’s Number Theory – why is $ℂ \otimes_ℚ K → K_ℂ,~z \otimes a ↦ (j(z)a)_τ$ an isomorphism?
157496
Determine the Galois group of $\mathbb{Q}(\sqrt{a+b\sqrt{d}})$
109801
multiplicative group of infinite fields
3161
Galois group of $x^6 + 3$ isomorphic to a copy of $S_3$ inside $S_6$
56647
Structure of $Gal(\mathbb{Q}(\zeta_{15})/\mathbb{Q})$?
157915
Isomorphism between the group $(\mathbb Z[x], +)$ and $(\mathbb Q_{>0}, .)$