User Fedor Petrov - MathOverflow

Fedor Petrov

Member for 13 years, 7 months
Last seen this week

pdmi.ras.ru/eng/perso/…
Saint-Petersburg, Russian Federation

147 Questions

Score Activity Newest Views

167 votes

50 answers

53k views

17 camels trick

asked Jun 7, 2017 at 13:52

54 votes

3 answers

8k views

If any open set is a countable union of balls, does it imply separability?

asked Sep 18, 2014 at 18:31

37 votes

5 answers

3k views

When factors may be cancelled in homeomorphic products?

asked May 29, 2010 at 21:26

31 votes

3 answers

2k views

Polynomials with the same values set on the unit circle

asked Jan 23, 2016 at 23:58

30 votes

4 answers

1k views

Resolution of multiple edges

asked Mar 14, 2019 at 21:58

30 votes

1 answer

926 views

partition of infinite word onto permitted words

asked Apr 30, 2014 at 14:04

29 votes

3 answers

4k views

Roots of permutations

asked Oct 11, 2010 at 13:48

27 votes

2 answers

5k views

Countable connected Hausdorff space

asked Nov 22, 2010 at 19:23

26 votes

2 answers

1k views

Partitions to different parts not exceeding $n$

asked Mar 13, 2011 at 12:46

25 votes

2 answers

6k views

Which finite groups have faithful complex irreducible representations?

asked Mar 2, 2011 at 16:41

25 votes

9 answers

3k views

triple with large LCM

asked Oct 10, 2010 at 17:25

24 votes

2 answers

1k views

Combinatorial meaning of the functional equation for logarithm

asked Nov 16, 2012 at 13:39

22 votes

5 answers

2k views

differential equation of conics

asked Sep 8, 2015 at 7:28

20 votes

1 answer

626 views

Combinatorial proof of a certain binomial identity

asked Feb 12 at 21:23

20 votes

3 answers

3k views

Proofs of parity results via the Handshaking lemma

asked Oct 12, 2011 at 8:33

19 votes

0 answers

507 views

univariate integer version of Hilbert's 17th problem

asked Oct 23, 2020 at 19:50

17 votes

1 answer

761 views

Is a facet always a maximal area section of a simplex?

asked Jan 31 at 15:49

17 votes

1 answer

805 views

Extreme points of convex compact sets

asked Sep 26, 2018 at 7:25

17 votes

2 answers

862 views

Why are the medians of a triangle concurrent? In absolute geometry

asked Oct 10, 2018 at 18:47

16 votes

2 answers

437 views

Does a certain points and lines configuration exist?

asked Jul 20, 2017 at 11:29

16 votes

1 answer

386 views

Maximal number of subsets in $\{1,\dots,n\}$ such that neither is contained in a union of two others

asked Aug 14, 2015 at 8:52

16 votes

1 answer

545 views

Computer software for periods

asked Mar 11, 2015 at 10:42

15 votes

1 answer

946 views

covering a separable metric space by small balls

asked Oct 11, 2010 at 23:00

15 votes

2 answers

1k views

sum of derivatives in roots of a polynomial of odd degree

asked Oct 10, 2010 at 9:25

15 votes

1 answer

363 views

separating points in $\mathbb{R}^d$ by minimal number of planes

asked Oct 5, 2015 at 18:12

15 votes

1 answer

2k views

How to prove that a monotone function is differentiable at some point?

asked Dec 2, 2015 at 19:10

15 votes

1 answer

559 views

Why sum of three squares of real polynomials is a sum of two squares?

asked Jun 18, 2016 at 9:59

15 votes

1 answer

512 views

Matrix with small elements and prescribed determinant

asked Feb 6, 2017 at 8:01

15 votes

1 answer

570 views

Higher arcsin wanted

asked Dec 6, 2017 at 19:27

15 votes

3 answers

367 views

Is primality essential in Varshamov's bound?

asked Jun 11, 2017 at 12:32

1