New posts in manifolds

How do you prove that the dunce cap is not a surface?

general-topology algebraic-topology manifolds surfaces

Can intersection of two manifolds be $xy=0$

manifolds examples-counterexamples

What are examples of parallelizable complex projective varieties?

algebraic-geometry differential-geometry algebraic-topology manifolds smooth-manifolds

Can $\mathbb C P^4$ be smoothly embedded in $\mathbb R^{12}$?

algebraic-topology manifolds differential-topology smooth-manifolds

Are there exotic balls?

general-topology algebraic-topology manifolds smooth-manifolds geometric-topology

Constructing Riemann surfaces

complex-analysis manifolds riemann-surfaces

Find a diffeomorphism between $SO(3)$ and $\mathbb{R}P^3$

general-topology differential-geometry manifolds differential-topology

Why is partition of unity required in definition of Sobolev space on manfolds?

partial-differential-equations manifolds sobolev-spaces

Is $x^3-6xy+y^2=-108$ a regular submanifold but not a regular $k$-submanifold?

general-topology geometry differential-geometry manifolds differential-topology

Exponential maps of $\mathbb{R}^n$ and $T^n$

manifolds lie-groups lie-algebras

Where does this permutation product live?

combinatorics differential-geometry permutations manifolds exterior-algebra

Prove that $\frac{H_1(\Sigma)}{[\alpha_1], \ldots, [\alpha_g], [\beta_1], \ldots, [\beta_g]} \cong H_1(Y)$

algebraic-topology manifolds homology-cohomology low-dimensional-topology mayer-vietoris-sequence

Is there an infinite dimensional Lie group associated to the Lie algebra of all vector fields on a manifold?

differential-geometry manifolds differential-topology lie-groups lie-algebras

Is a smooth immersion $c: [a,b] \to M$ injective if its image is a 1-manifold with non-empty boundary?

general-topology differential-geometry manifolds differential-topology orientation

Does the Jordan-Brouwer Separation Theorem require smoothness and orientability of the hypersurface?

general-topology geometry differential-geometry manifolds differential-topology

How to show that the unit sphere is a topological manifold?

general-topology manifolds

What is the best way to define the tangent space of a manifold?

differential-geometry manifolds tangent-spaces

How is the inclusion map both an Immersion and Submersion between Manifolds

differential-geometry manifolds smooth-manifolds inclusion-exclusion tangent-spaces

Transition functions in manifold

Can speed be defined for a parametrized but irregular curve in a Riemannian manifold?

general-topology proof-verification differential-geometry manifolds riemannian-geometry