User Sergei Ivanov

58 votes

9 answers

8k views

How do they verify a verifier of formalized proofs?

asked Mar 16, 2010 at 20:48

33 votes

1 answer

4k views

Is every smooth function Lebesgue-Lebesgue measurable?

asked Mar 26, 2010 at 20:44

30 votes

2 answers

3k views

An unfair marriage lemma

asked Apr 23, 2015 at 18:14

27 votes

2 answers

2k views

A set that can be covered by arbitrarily small intervals

asked Dec 6, 2010 at 16:05

26 votes

6 answers

3k views

Easy proof of the fact that isotropic spaces are Euclidean

asked Oct 5, 2010 at 21:52

25 votes

3 answers

2k views

Are fundamental groups of aspherical manifolds Hopfian?

asked Apr 9, 2010 at 12:16

24 votes

1 answer

3k views

What can be tiled by T-tetrominoes?

asked Jun 20, 2010 at 20:18

24 votes

3 answers

1k views

Isoperimetric inequality on a Riemannian sphere

asked May 5, 2013 at 20:31

20 votes

1 answer

936 views

A collection of intervals that can cover any measure zero set

asked Dec 7, 2010 at 11:43

18 votes

5 answers

3k views

Smoothness of $f(\sqrt x)$

asked Oct 4, 2011 at 10:19

17 votes

3 answers

2k views

Is there Domain Invariance for Alexandrov spaces?

asked Apr 15, 2010 at 22:34

16 votes

1 answer

511 views

Subdividing a polyhedral space into convex simplices

asked Nov 16, 2010 at 0:31

14 votes

1 answer

593 views

Rational approximations on the circle

asked Apr 19, 2011 at 9:57

14 votes

1 answer

2k views

Invariance of the l.h.s. of Euler-Lagrange equation

asked Apr 2, 2013 at 14:52

13 votes

3 answers

2k views

Metric angles in Riemannian manifolds of low regularity

asked Oct 11, 2010 at 18:07

13 votes

3 answers

3k views

Contractible manifold with boundary - is it a disc?

asked Mar 19, 2010 at 22:03

11 votes

1 answer

1k views

In a locally CAT(k) space, does uniqueness of geodesics imply the lack of conjugate points?

asked Mar 30, 2010 at 23:20

10 votes

2 answers

1k views

Are operators with trivial spectrum nilpotent in a sense?

asked May 15, 2010 at 8:41

9 votes

3 answers

708 views

surfaces of constant centro-affine curvature

asked Apr 13, 2011 at 23:19

9 votes

1 answer

321 views

Convex body with affine-equivalent cross-sections

asked Mar 10, 2016 at 22:21

8 votes

1 answer

382 views

Estimating flat norm distance from a planar disc

asked Mar 11, 2010 at 22:29

8 votes

2 answers

425 views

Are there arbitrarily sparse "lattices" in negatively curved symmetric spaces?

asked May 29, 2010 at 22:20

7 votes

3 answers

648 views

Is it decidable whether a given set generates the whole group?

asked Apr 4, 2010 at 21:11

6 votes

5 answers

2k views

A book explaining power and limitations of Peano Axioms?

asked Mar 21, 2010 at 11:37

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24 Questions

How do they verify a verifier of formalized proofs?

Is every smooth function Lebesgue-Lebesgue measurable?

An unfair marriage lemma

A set that can be covered by arbitrarily small intervals

Easy proof of the fact that isotropic spaces are Euclidean

Are fundamental groups of aspherical manifolds Hopfian?

What can be tiled by T-tetrominoes?

Isoperimetric inequality on a Riemannian sphere

A collection of intervals that can cover any measure zero set

Smoothness of $f(\sqrt x)$

Is there Domain Invariance for Alexandrov spaces?

Subdividing a polyhedral space into convex simplices

Rational approximations on the circle

Invariance of the l.h.s. of Euler-Lagrange equation

Metric angles in Riemannian manifolds of low regularity

Contractible manifold with boundary - is it a disc?

In a locally CAT(k) space, does uniqueness of geodesics imply the lack of conjugate points?

Are operators with trivial spectrum nilpotent in a sense?

surfaces of constant centro-affine curvature

Convex body with affine-equivalent cross-sections

Estimating flat norm distance from a planar disc

Are there arbitrarily sparse "lattices" in negatively curved symmetric spaces?

Is it decidable whether a given set generates the whole group?

A book explaining power and limitations of Peano Axioms?