The topology on $\mathbb A^2$ is not the product topology
62128
Zariski Topology question
24351
The ring $\Bbb Z\left [\frac{-1+\sqrt{-19}}{2}\right ]$ is not a Euclidean domain
70576
Elementary proof that $\mathbb{R}^n$ is not homeomorphic to $\mathbb{R}^m$
118622
Local diffeomorphism from $\mathbb R^2$ onto $S^2$
48557
Product of connected spaces
73927
Is $\mathbb{R}$ a subset of $\mathbb{R}^2$?
151637
How do we prove that this set is not manifold?
138653
Is $\mathbb{R}$ a subspace of $\mathbb{R}^2$?
67383
Prove that $G'$ is not planar.
143831
Showing $\mathbb{Q}$ is homeomorphic to $\mathbb{Q}^2$
131890
Totally disconnected space that is not $T_2$
85870
Show this set is a base for some topology on $\mathbb{Z}$
80100
Boundary of product manifolds such as $S^2 \times \mathbb R$
133820
The product topology on $\mathbb R_d\times \mathbb R$ vs. the dictionary order topology on $\mathbb R\times \mathbb R$
2348
Show that the sphere, S, and $\mathbb{R}^2$ is not homeomorphic
13620
$\omega_2$ is a not countable union of countable sets without AC
78513
Show finite complement topology is, in fact, a topology