How come $(\mathbb{R},\cdot)$ does not form a group?
2458
Multiplicative group $(\mathbb R^*, ×)$ is group but $(\mathbb R, ×)$ is not group, why?
66272
Is there a common notion of $\mathbb{R}^n$, for non-integer $n$?
151210
How can we find and categorize the subgroups of $\mathbb{R}$?
116168
Is $e^x$ the only isomorphism between the groups $(\mathbb{R},+)$ and $(\mathbb{R}_{> 0},*)$?
75970
$\mathbb Z[1/2]$ is not finitely generated?
84869
Are the groups $\mathbb{C}$ and $\mathbb{R}$ isomorphic?
55769
Why is there no functor $\mathsf{Group}\to\mathsf{AbGroup}$ sending groups to their centers?
78006
What is known about the quotient group $\mathbb{R} / \mathbb{Q}$?
3296
Proof That $\mathbb{R} \setminus \mathbb{Q}$ Is Not an $F_{\sigma}$ Set
126771
Group element not taken to its inverse by any automorphism
723
Is there a constructive way to exhibit a basis for $\mathbb{R}^\mathbb{N}$?
90071
Why don't we have an isomorphism between $R[x]$ and $ R[[x]]$?
35569
Prove that $[0,1]$ isn't homeomorphic to $\mathbb{R}$
67374
Is it true that $\mathbb{R}$ and $\mathbb{R}^2$ are isomorphic as abelian groups?
55902
Show $R[x]/(x)\cong R$
97391
Prove that $(C^1[0,1], \|\cdot\|)$ is not a Banach space
67383
Prove that $G'$ is not planar.