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Sergei Ivanov
  • Member for 12 years, 5 months
  • Last seen more than a month ago
56 votes
9 answers
8k views

How do they verify a verifier of formalized proofs?

32 votes
1 answer
3k views

Is every smooth function Lebesgue-Lebesgue measurable?

27 votes
2 answers
2k views

An unfair marriage lemma

26 votes
6 answers
3k views

Easy proof of the fact that isotropic spaces are Euclidean

26 votes
2 answers
2k views

A set that can be covered by arbitrarily small intervals

25 votes
3 answers
2k views

Are fundamental groups of aspherical manifolds Hopfian?

24 votes
1 answer
3k views

What can be tiled by T-tetrominoes?

24 votes
3 answers
1k views

Isoperimetric inequality on a Riemannian sphere

20 votes
1 answer
852 views

A collection of intervals that can cover any measure zero set

17 votes
3 answers
1k views

Is there Domain Invariance for Alexandrov spaces?

17 votes
5 answers
2k views

Smoothness of $f(\sqrt x)$

16 votes
1 answer
486 views

Subdividing a polyhedral space into convex simplices

14 votes
1 answer
555 views

Rational approximations on the circle

13 votes
3 answers
1k views

Metric angles in Riemannian manifolds of low regularity

13 votes
3 answers
2k views

Contractible manifold with boundary - is it a disc?

12 votes
1 answer
1k views

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

10 votes
1 answer
1k views

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

10 votes
2 answers
917 views

Are operators with trivial spectrum nilpotent in a sense?

9 votes
3 answers
644 views

surfaces of constant centro-affine curvature

8 votes
1 answer
368 views

Estimating flat norm distance from a planar disc

8 votes
2 answers
376 views

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

7 votes
3 answers
570 views

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

7 votes
1 answer
264 views

Convex body with affine-equivalent cross-sections

6 votes
5 answers
2k views

A book explaining power and limitations of Peano Axioms?