User Crostul

21 votes

1 answer

1k views

Is the ring of holomorphic functions on $S^1$ Noetherian?

asked Jul 29, 2015 at 15:46

17 votes

4 answers

621 views

Compute the limit $\lim\limits_{t \to + \infty} \int_0^{+ \infty} \frac{ \mathrm d x}{e^x+ \sin tx} $

asked Sep 22, 2020 at 22:26

15 votes

1 answer

313 views

Study of rings of the form $R+I$

asked May 31, 2015 at 10:16

12 votes

1 answer

258 views

On the theorem "$3$ is everywhere"

asked Mar 3, 2016 at 15:51

11 votes

1 answer

287 views

On uniqueness of sums of prime powers

asked Jan 10, 2018 at 14:20

11 votes

1 answer

152 views

Compute the value of the integral $\int_1^{\infty} \lfloor x^2 \rfloor e^{-x} \ \mathrm d x $

asked Aug 13, 2020 at 8:53

8 votes

1 answer

372 views

When is a monoid contained in a group?

asked May 7, 2015 at 17:57

7 votes

1 answer

1k views

On semisimple rings

asked Mar 30, 2015 at 9:59

5 votes

1 answer

426 views

Is $\mathbb{Q}$ homeomorphic to its open subintervals?

asked Jun 26, 2014 at 17:33

5 votes

1 answer

97 views

Number field attached to a finite group.

asked May 4, 2015 at 14:31

5 votes

2 answers

127 views

About the limit $\lim_{n \to +\infty} \frac{1}{n^2} \sum_{1 \le a,b \le n} \frac{1}{ \mathrm{gcd} (a,b)} $

asked Mar 17, 2019 at 10:57

4 votes

1 answer

129 views

A convex closed set with disconnected boundary: is it necessarily a strip?

asked Aug 1, 2020 at 14:35

4 votes

0 answers

42 views

Can we associate values to elements in a poset? [duplicate]

asked Feb 11, 2016 at 17:31

4 votes

2 answers

227 views

For which values of real $\alpha, \beta$ does $\sum_{n,m \ge 1} \frac{1}{n^{\alpha}+ m^{\beta}}$ converge?

asked May 25, 2016 at 23:14

4 votes

1 answer

234 views

Is a locally $\mathcal{C}$ space a direct limit of $\mathcal{C}$ spaces?

asked Jun 13, 2015 at 9:19

4 votes

1 answer

247 views

A generalization of Jordan curve theorem involving Warsaw circle

asked Aug 12, 2015 at 16:52

4 votes

2 answers

152 views

Conditions on couples of elements to generate the same ideal

asked Oct 30, 2015 at 11:31

3 votes

1 answer

139 views

On a theorem of Akizuki concerning the minimal number of generators of an ideal

asked Jul 22, 2015 at 10:49

3 votes

1 answer

469 views

Subgroups of the reals of finite index.

asked Dec 31, 2014 at 10:09

3 votes

1 answer

1k views

Density of a set of numbers.

asked May 29, 2016 at 13:52

2 votes

1 answer

105 views

Is every ring a quotient of a zero-characteristic ring?

asked Sep 21, 2016 at 13:34

2 votes

1 answer

64 views

The set $\{ g \in G | gK_1 \cap K_2 = \emptyset \}$ is open

asked Mar 10, 2020 at 13:23

2 votes

2 answers

63 views

For any permutation $\sigma$ of $\{ 1, \dots ,n \}$ there exists $k$ such that $|k- \sigma (k)| \le \frac{n}{2}$

asked Apr 24, 2019 at 20:19

2 votes

1 answer

67 views

Find a hyperplane not intersecting $S$

asked Dec 20, 2014 at 15:43

2 votes

1 answer

94 views

If $G_{ab}$ is cyclic then $G$ is cyclic

asked Apr 27, 2015 at 17:17

2 votes

1 answer

55 views

If $V,W$ are valuation domains, then $V+W$ is a ring.

asked Sep 29, 2015 at 16:28

1 vote

2 answers

50 views

If $f:[0,1] \longrightarrow \mathbb{R}$ is $C^{\infty}$, can we say that it is positive or negative?

asked Oct 7, 2015 at 12:43

1 vote

0 answers

42 views

Characterization of valuation domains by means of their maximal ideal

asked Sep 15, 2015 at 17:55

1 vote

0 answers

61 views

Given two rationals $s,p$, do they exist three rationals whose sum is $s$ and product is $p$?

asked Mar 14, 2018 at 17:51

1 vote

1 answer

105 views

Non trivial solutions for the diophantine $X^2Y+XY^2+XYZ-Z^3=0$

asked Mar 19, 2018 at 12:43

Stack Exchange Network

35 Questions

Is the ring of holomorphic functions on $S^1$ Noetherian?

Compute the limit $\lim\limits_{t \to + \infty} \int_0^{+ \infty} \frac{ \mathrm d x}{e^x+ \sin tx} $

Study of rings of the form $R+I$

On the theorem "$3$ is everywhere"

On uniqueness of sums of prime powers

Compute the value of the integral $\int_1^{\infty} \lfloor x^2 \rfloor e^{-x} \ \mathrm d x $

When is a monoid contained in a group?

On semisimple rings

Is $\mathbb{Q}$ homeomorphic to its open subintervals?

Number field attached to a finite group.

About the limit $\lim_{n \to +\infty} \frac{1}{n^2} \sum_{1 \le a,b \le n} \frac{1}{ \mathrm{gcd} (a,b)} $

A convex closed set with disconnected boundary: is it necessarily a strip?

Can we associate values to elements in a poset? [duplicate]

For which values of real $\alpha, \beta$ does $\sum_{n,m \ge 1} \frac{1}{n^{\alpha}+ m^{\beta}}$ converge?

Is a locally $\mathcal{C}$ space a direct limit of $\mathcal{C}$ spaces?

A generalization of Jordan curve theorem involving Warsaw circle

Conditions on couples of elements to generate the same ideal

On a theorem of Akizuki concerning the minimal number of generators of an ideal

Subgroups of the reals of finite index.

Density of a set of numbers.

Is every ring a quotient of a zero-characteristic ring?

The set $\{ g \in G | gK_1 \cap K_2 = \emptyset \}$ is open

For any permutation $\sigma$ of $\{ 1, \dots ,n \}$ there exists $k$ such that $|k- \sigma (k)| \le \frac{n}{2}$

Find a hyperplane not intersecting $S$

If $G_{ab}$ is cyclic then $G$ is cyclic

If $V,W$ are valuation domains, then $V+W$ is a ring.

If $f:[0,1] \longrightarrow \mathbb{R}$ is $C^{\infty}$, can we say that it is positive or negative?

Characterization of valuation domains by means of their maximal ideal

Given two rationals $s,p$, do they exist three rationals whose sum is $s$ and product is $p$?

Non trivial solutions for the diophantine $X^2Y+XY^2+XYZ-Z^3=0$