User Pietro Majer

45 votes

10 answers

10k views

The functional equation $f(f(x))=x+f(x)^2$

asked Dec 17, 2010 at 12:27

28 votes

6 answers

5k views

I know that you know...

asked Nov 23, 2012 at 14:57

27 votes

4 answers

3k views

Genealogy of the Lagrange inversion theorem

asked May 21, 2010 at 14:38

27 votes

1 answer

2k views

Is every real number in [0,1] a product of three (or more) Cantor set's numbers?

asked Dec 22, 2023 at 12:42

25 votes

3 answers

2k views

Asymptotic growth of a certain integer sequence

asked Aug 28, 2010 at 20:16

24 votes

1 answer

2k views

A puzzle about finding three points $(x,y)$, $(x,z)$ and $(y,z)$ in a subset of a square.

asked Feb 25, 2011 at 11:25

24 votes

4 answers

2k views

Why the sequence of Bernstein polynomials of $\sqrt x$ is increasing?

asked Jan 16, 2021 at 16:30

22 votes

3 answers

806 views

Best Hölder exponents of surjective maps from the unit square to the unit cube

asked Apr 27, 2015 at 8:14

21 votes

1 answer

1k views

Banach spaces with few linear operators ?

asked Jul 5, 2010 at 20:22

21 votes

0 answers

717 views

Closed connected additive subgroups of the Hilbert space

asked Nov 8, 2010 at 16:48

19 votes

2 answers

2k views

Integral representation of higher order derivatives

asked May 17, 2011 at 18:40

19 votes

1 answer

3k views

Infinite convex combinations in a Banach space

asked Feb 21, 2011 at 10:19

18 votes

0 answers

560 views

Fundamental Theorem of Algebra via multiple integrals

asked Jan 28, 2021 at 16:01

18 votes

3 answers

713 views

Ergodic limits along subsets of $\mathbb{N}.$

asked Oct 23, 2010 at 14:38

16 votes

3 answers

2k views

Periodic orbits and polynomials

asked May 26, 2010 at 15:43

15 votes

1 answer

1k views

Intersection of complemented subspaces of a Banach space

asked Jan 12, 2012 at 14:29

15 votes

5 answers

2k views

Between Tietze's and Dugundji's extension theorems

asked Apr 1, 2015 at 17:04

14 votes

1 answer

839 views

What are the applications of the Mazur-Ulam Theorem?

asked Sep 27, 2019 at 13:17

13 votes

1 answer

688 views

Including a Jordan arc into a Jordan loop (Can the Magi go home by another way?)

asked Sep 12, 2011 at 11:19

12 votes

6 answers

3k views

Reference request: an elementary proof of Brouwer fixed-point theorem.

asked Sep 24, 2012 at 11:08

11 votes

0 answers

424 views

Maximizing the volume in a family of subsets of a cube

asked Jun 27, 2010 at 9:28

11 votes

0 answers

159 views

Bijections $\mathbb{Z}\times\mathbb{Z}\to\mathbb{Z}$ with vanishing local means

asked Jul 26, 2019 at 14:21

11 votes

1 answer

280 views

Which closed subsets $Y$ of a compact space $X$ admit a linear extensor $C(Y)\to C(X)$?

asked Feb 19 at 9:41

11 votes

2 answers

296 views

Connecting a compact subset by a simple curve

asked Jan 10, 2021 at 11:54

10 votes

1 answer

864 views

The closures in $C^0(\mathbb{R}, \mathbb{R})$ of the set of integer valued polynomials, resp, of polynomials with integer coefficients

asked Dec 29, 2010 at 13:48

10 votes

2 answers

2k views

The different Branches of Arithmetic

asked Jan 26, 2011 at 15:52

10 votes

5 answers

1k views

Convex curves with many inscribed triangles maximizing perimeter

asked Oct 14, 2011 at 19:41

9 votes

1 answer

858 views

Perturbations of an operator that disconnect the spectrum

asked May 14, 2010 at 22:54

8 votes

1 answer

724 views

Sticks and thread

asked Jun 26, 2010 at 8:40

8 votes

3 answers

2k views

Multiplicative integral of $\Gamma(x)$

asked Jul 22, 2010 at 13:47

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56 Questions

The functional equation $f(f(x))=x+f(x)^2$

I know that you know...

Genealogy of the Lagrange inversion theorem

Is every real number in [0,1] a product of three (or more) Cantor set's numbers?

Asymptotic growth of a certain integer sequence

A puzzle about finding three points $(x,y)$, $(x,z)$ and $(y,z)$ in a subset of a square.

Why the sequence of Bernstein polynomials of $\sqrt x$ is increasing?

Best Hölder exponents of surjective maps from the unit square to the unit cube

Banach spaces with few linear operators ?

Closed connected additive subgroups of the Hilbert space

Integral representation of higher order derivatives

Infinite convex combinations in a Banach space

Fundamental Theorem of Algebra via multiple integrals

Ergodic limits along subsets of $\mathbb{N}.$

Periodic orbits and polynomials

Intersection of complemented subspaces of a Banach space

Between Tietze's and Dugundji's extension theorems

What are the applications of the Mazur-Ulam Theorem?

Including a Jordan arc into a Jordan loop (Can the Magi go home by another way?)

Reference request: an elementary proof of Brouwer fixed-point theorem.

Maximizing the volume in a family of subsets of a cube

Bijections $\mathbb{Z}\times\mathbb{Z}\to\mathbb{Z}$ with vanishing local means

Which closed subsets $Y$ of a compact space $X$ admit a linear extensor $C(Y)\to C(X)$?

Connecting a compact subset by a simple curve

The closures in $C^0(\mathbb{R}, \mathbb{R})$ of the set of integer valued polynomials, resp, of polynomials with integer coefficients

The different Branches of Arithmetic

Convex curves with many inscribed triangles maximizing perimeter

Perturbations of an operator that disconnect the spectrum

Sticks and thread

Multiplicative integral of $\Gamma(x)$