Changyu Guo's user avatar
Changyu Guo's user avatar
Changyu Guo's user avatar
Changyu Guo
  • Member for 11 years, 6 months
  • Last seen more than 1 year ago
8 votes
1 answer
1k views

How many ways do we have to prove that a mapping is open?

7 votes
2 answers
1k views

Does anyone know what is the right reference for the following simple lemma from harmonic analysis?

6 votes
0 answers
214 views

Are there any known ``topological" invariants for branched coverings?

5 votes
1 answer
168 views

Antoine's Necklace and positive Hausdorff/Lebesgue measure

5 votes
2 answers
760 views

A question on density of Lipschitz functions in weighted Sobolev spaces

5 votes
1 answer
474 views

On a.e. approximate differentiability of certain continuous real functions

5 votes
2 answers
605 views

Good references on the theory of harmonic mappings between Riemannian manifolds

4 votes
1 answer
569 views

A lower-dimensional algebraic topology problem between homology group and fundamental group

4 votes
1 answer
674 views

Is there an elementary proof of the polar factorization theorem for vector-valued function?

3 votes
1 answer
512 views

Is there a direct proof of the following real analysis fact?

3 votes
1 answer
778 views

A closed connected component in a topological space does not contain any path-connected subset?

3 votes
1 answer
922 views

A good reference for uniformization theorem for compact and non-compact Riemann surface

2 votes
0 answers
60 views

Removable sets for simply connectedness of a differentiable manifold

2 votes
1 answer
111 views

Regularity of decomposition of matrix-valued function

2 votes
1 answer
192 views

On differentiability relative to a n-rectifiable subset of $\mathbb{R^N}$

2 votes
1 answer
495 views

On triangle comparison in Riemannian manifolds with upper sectional curvature bound

1 vote
2 answers
642 views

Can we extend an a.e. Lipschitz map defined on a closed subset of R^N to the whole space so that it is still a.e. Lipschitz?

1 vote
0 answers
45 views

Does the following measurable Halmilton-Jacobian equation admit a Lipschitz solution?

1 vote
0 answers
116 views

How to define the determinant of a morphism between graded Lie algebras?

1 vote
0 answers
256 views

Is this a "new" terminology in homology/cohomology theory?

1 vote
0 answers
167 views

How many ways we have to prove that a topologically (or analytically) nice mapping is injective?

0 votes
1 answer
510 views

One-dimensional Hausdorff measure of preimages