Proving $\mathbb{Q}$ not isomorphic to $\mathbb{R}^{+}$
108955
Showing $(\mathbb{Q},+)$ is not isomorphic to $(\mathbb{R},+)$
41846
$(\mathbb{R}^n,\|\cdot\|_{p})$ is isometrically isomorphic to $(\mathbb{R}^n,\|\cdot\|_{q})$ iff $p=q,$
25050
To prove that $(F,+)$ and $(F-\{0\},\cdot)$ are not isomorphic as groups.
88474
$\mathbb{A}^{2}$ not isomorphic to affine space minus the origin
66238
Proving $\mathbb{Z}[\sqrt {10}]$ is not a UFD
86542
Group of positive rationals under multiplication not isomorphic to group of rationals
30753
Showing there is no ring whose additive group is isomorphic to $\mathbb{Q}/\mathbb{Z}$
84114
Does there exist a surjective homomorphism from $(\mathbb R,+)$ to $(\mathbb Q,+)$ ?
156766
Prove that $\sqrt{\frac{n}{n+1}}\notin \mathbb{Q}$
121361
Showing that $\lnot Q \lor (\lnot Q \land R) = \lnot Q$ without a truth table
67374
Is it true that $\mathbb{R}$ and $\mathbb{R}^2$ are isomorphic as abelian groups?
53331
$\mathbb{Q}(\sqrt2, \sqrt3)$ is not isomorphic to $\mathbb{Q}(\sqrt[4]2)$
57166
Showing that $\Bbb R[x] / \langle x^2 + 1 \rangle$ is isomorphic to $\Bbb C$ question
3296
Proof That $\mathbb{R} \setminus \mathbb{Q}$ Is Not an $F_{\sigma}$ Set
104562
Prove that $\mathbb{Z}$ is not isomorphic to additive group of any vector space over any field.
115270
What are the generators of $(\mathbb{R},+)$?
126927
$\mathbb Q$ is not the direct product of two non-trivial groups.