Show the klein group and  is not isomorphic
98601
Any  group of order four is either cyclic or isomorphic to $V$
33370
Show that the one point compactification of $\mathbb{Q}$ is not Hausdorff
141265
Finding a normal and not normal subgroup of $S_3$
23077
Prove that the dihedral group $D_4$ can not be written as a direct product of two groups
93169
Show that $(\mathbb Z[x],+)$ and $(\mathbb Q_{>0},\cdot)$ are isomorphic groups
135241
Show that $\mathbb{Z}/n^2\mathbb{Z}$ is not isomorphic to other group
58707
Prove Quotient Group Isomorphism
155669
$\mathrm{Aut}(D_4)$ is isomorphic to $D_4$
48962
Show the two fields are not isomorphic
88474
$\mathbb{A}^{2}$ not isomorphic to affine space minus the origin
128096
Let V denote the Klein 4-group. Show that $\text{Aut} (V)$ is isomorphic to $S_3$
134686
$D_3\oplus D_4$ not isomorphic to $D_{24}$
102622
K is a subgroup of G. Show that K is not a normal subgroup
99538
Non-trivial groups pairwise non-isomorphic with isomorphic direct products
112263
an example for $\pi$-quasinormal subgroup but is not normal
9140
Show $\operatorname{Aut}(C_2 \times C_2)$ is isomorphic to $S_3=D_6$
99382
What is needed to make Euclidean spaces isomorphic as groups?