A regular surface with non zero mean curvature is orientable
141031
Surface with non-zero mean curvature means orientable
106298
Prove that some topology is not metrizable
23414
Topologist's Sine Curve: A rigorous proof of why $\overline{S} = S \cup V$
79615
Manifold is not orientable
132911
Determining if there can be smooth closed geodesic given its curvature
155291
Prove that for any piecewise smooth curve it is possible to find the parametrisation
51546
Geometrical Interpertation of Cauchy's Mean Value Theorem
142503
There are no compact minimal surfaces
156302
Find conditions for a surface of rotation to be regular
137071
Orientation of hypersurface
102297
Construction of a regular pentagon
67009
Show $H_2(M, \mathbb{Z}) = \mathbb{Z^r}$ if $M$ is orientable, $\mathbb{Z^{r-1}} \oplus \mathbb{Z_2}$ if nonorientable
5303
isolated non-normal surface singularity
46309
Prove that this graph is nonplanar
122352
Topologies in a Riemannian Manifold
30898
Orientability of projective space
15645
Is convex open set in $\mathbb{R}^n$ is regular?