(Q,+) and (C*,+) has no finite index subgroup
64408
Subgroup of $\mathbb{Q}$ with finite index
47824
Calculation of subgroups of $(Z_{12}, +)$
99309
Groups of order $n^2$ that have no subgroup of order $n$
62635
Prove that the additive group $ℚ$ is not isomorphic with the multiplicative group $ℚ^*$.
86015
$\mathbb Q[x]/(x^2+1)$ is not isomorphic to $\mathbb Q[x]/(x^2+2)$
95534
If $|G|=p^nq$, then $G$ contains a unique normal subgroup of index $q$
55769
Why is there no functor $\mathsf{Group}\to\mathsf{AbGroup}$ sending groups to their centers?
108955
Showing $(\mathbb{Q},+)$ is not isomorphic to $(\mathbb{R},+)$
104080
Group with order $pq$ has subgroups of order $p$ and $q$
75012
Additive group of rationals has no minimal generating set
95240
Show that $({\mathbb{Q}},+)$ is not finitely generated using the Fundamental Theorem of Finitely Generated Abelian Groups.
17378
Characterize finite dimensional algebras without nilpotent elements
41231
Subgroups of (Z,+) of order n
8746
Groups of order $pq$ without using Sylow theorems
87534
Finitely generated group which is not finitely presented
78048
Group of order 24 with no element of order 6 is isomorphic to $S_4$
33338
Problem on $\operatorname{Hom}(\mathbb Z_6,R^*\oplus C^*)$