Fedor Petrov's user avatar
Fedor Petrov's user avatar
Fedor Petrov's user avatar
Fedor Petrov
  • Member for 14 years, 1 month
  • Last seen this week
167 votes
50 answers
55k views

17 camels trick

54 votes
3 answers
9k views

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

37 votes
5 answers
3k views

When factors may be cancelled in homeomorphic products?

31 votes
3 answers
2k views

Polynomials with the same values set on the unit circle

30 votes
4 answers
1k views

Resolution of multiple edges

30 votes
1 answer
935 views

partition of infinite word onto permitted words

29 votes
3 answers
4k views

Roots of permutations

27 votes
2 answers
6k views

Countable connected Hausdorff space

26 votes
2 answers
6k views

Which finite groups have faithful complex irreducible representations?

26 votes
2 answers
1k views

Partitions to different parts not exceeding $n$

26 votes
9 answers
3k views

triple with large LCM

24 votes
2 answers
1k views

Combinatorial meaning of the functional equation for logarithm

22 votes
5 answers
2k views

differential equation of conics

21 votes
1 answer
713 views

Combinatorial proof of a certain binomial identity

20 votes
3 answers
3k views

Proofs of parity results via the Handshaking lemma

19 votes
0 answers
519 views

univariate integer version of Hilbert's 17th problem

17 votes
1 answer
788 views

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

17 votes
1 answer
832 views

Extreme points of convex compact sets

17 votes
2 answers
916 views

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

16 votes
2 answers
449 views

Does a certain points and lines configuration exist?

16 votes
1 answer
590 views

Higher arcsin wanted

16 votes
1 answer
390 views

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

16 votes
1 answer
549 views

Computer software for periods

15 votes
1 answer
966 views

covering a separable metric space by small balls

15 votes
2 answers
1k views

sum of derivatives in roots of a polynomial of odd degree

15 votes
1 answer
371 views

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

15 votes
1 answer
2k views

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

15 votes
1 answer
569 views

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

15 votes
1 answer
539 views

Matrix with small elements and prescribed determinant

15 votes
3 answers
371 views

Is primality essential in Varshamov's bound?

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