Null-homotopic closed curve in a Jordan domain
64084
Existence of a simple closed curve which is not null-homotopic
129288
proof that topologist sine curve is not locally connected
10215
Differentiable manifolds as locally ringed spaces
11319
Is $M=\{(x,|x|): x \in (-1, 1)\}$ not a differentiable manifold?
51577
Non-existence of a bijective analytic function between annulus and punctured disk
132911
Determining if there can be smooth closed geodesic given its curvature
119452
Nilpotent matrices with same minimal polynomial and nullity
23414
Topologist's Sine Curve: A rigorous proof of why $\overline{S} = S \cup V$
152442
An annulus in $\mathbb R^2$ is path connected
155244
Holomorphic self map on the open unit disc
27096
Hilbert polynomial of an hypersurface in projective space
106050
Finding a conformal map from the intersection of two disks to the unit disk.
117104
Is the punctured plane homotopy equivalent to the circle?
93160
Null Space of Transformation
153767
Singular points and tangent lines
121995
Hilbert's Nullstellensatz implies $I(Z(I)) = \sqrt{I}$
151735
$\mathbb{R}^3 \setminus A$ deformation retracts onto $S^1 \vee S^2$