Why is this a smooth manifold?
13964
Manifold of Density Matrices
118622
Local diffeomorphism from $\mathbb R^2$ onto $S^2$
75391
How to prove that a left-invariant metric on a Lie group is smooth?
83874
Prove that Hopf maps on $S^3, S^2$ and $\mathbb{C} \mathbb{P}^1$ are smooth submersions
155060
Confusion about definition of manifold with boundary
128862
Prove no existing a smooth function satisfying ... related to Morse Theory
99230
If a manifold M has zero Euler characteristic, there is a non-vanishing vector field on it
132911
Determining if there can be smooth closed geodesic given its curvature
84419
Product of manifolds & orientability
89649
Linear Algebra munkres analysis on manifolds question.
99755
Non-orientable 1-dimensional (non-hausdorff) manifold
10215
Differentiable manifolds as locally ringed spaces
137093
What is the codimension of matrices of rank $r$ as a manifold?
112607
Why is homology invariant under deformation retraction/homotopy equivalence?
157742
Prove that $U(n)$ is a manifold
135059
Prove that the unit circle, $S^1:=\{(x,y)\in \mathbb{R}^2: x^2+y^2=1\}$, Is a one-dimensional manifold
94215
Fundamental group of the connected sum of manifolds