$\text{Aut}(\Bbb Z_n) \cong U(n)$
40321
$\operatorname{Aut}(\mathbb Z_n)$ is isomorphic to $U_n$.
96380
Representation of $\text{sl}(2,\mathbb{C})$
66806
A nonsplit short exact sequence of abelian groups with $B \cong A \oplus C$
9129
Show that $\mathbb{Q}(\zeta_n)$ is Galois over $\mathbb{Q}$ and $Gal(\mathbb{Q}(\zeta_n)/\mathbb{Q}))\cong \mathbb{Z_n}^*$
76685
Determine $\text{Aut}(S)$ where $S = \mathbb{Q}[x]/(x^2)$
118898
Is there a simple way of proving that $\text{GL}_n(R) \not\cong \text{GL}_m(R)$?
66020
What is $\mathbb Z[[t]]$? What are the double brackets?
120594
$\mathbb Z[i]/ \langle 1+2i \rangle \cong \mathbb Z_5$
13761
Automorphisms in $\mathbb{Z}_n$
24561
$\mathbb S_n$ as semidirect product
128711
$(\Bbb Z\oplus \Bbb Z)[X] \not\cong \Bbb Z[X]\oplus \Bbb Z[X]\,$?
70861
$\mathbb P^n\times \mathbb P^m\not\cong \mathbb P^{m+n}$
149578
Subgroups of $(\mathbb Z_n,+)$
145752
Aut $\mathbb Z_p\simeq \mathbb Z_{p-1}$
9140
Show $\operatorname{Aut}(C_2 \times C_2)$ is isomorphic to $S_3=D_6$
61226
Group Structure on $\Bbb R$
94090
How to show that for any abelian group $G$, $\text{Hom}(\mathbb{Z},G)$ is isomorphic to $G$