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7 votes

3 answers

278 views

Pointwise convergence of sequence $(f_n)_n$ of functions to $f$ and changing limits

asked Aug 20, 2018 at 20:21

6 votes

3 answers

142 views

Supplementary exercise 51, chapter 3 from 'A walk through combinatorics' 4th edition

asked Dec 29, 2022 at 11:50

5 votes

1 answer

6k views

Tensor product of localization is isomorphic to localization of tensor product

asked Jan 15, 2017 at 20:24

5 votes

2 answers

758 views

Compute $5!25! \mod 31$

asked Feb 17, 2017 at 11:56

5 votes

5 answers

169 views

Computing $7^{13} \mod 40$

asked Feb 17, 2017 at 17:38

4 votes

2 answers

495 views

Inverse image of a Noetherian module under a module morphism

asked Jan 14, 2017 at 10:28

4 votes

1 answer

413 views

isomorphic extension fields of the $p$-adic numbers

asked May 2, 2017 at 14:57

4 votes

2 answers

64 views

If $x = y^3$ in $\mathbb{Z} + \frac{-1 + \sqrt{-3}}{2}\mathbb{Z}$, then there is some $w \in \mathbb{Z} + \sqrt{-3}\mathbb{Z}$ such that $x = w^3$.

asked May 15, 2017 at 10:59

4 votes

1 answer

96 views

Subgroups of finitely generated group are not necessarily finitely generated (proof).

asked Apr 2, 2021 at 18:40

4 votes

2 answers

518 views

Restriction of homomorphism to finite index subgroup gives finite index subgroup of kernel

asked Apr 25, 2018 at 21:20

4 votes

1 answer

395 views

Prove that the following map has at least $k-2$ fixed points

asked Nov 8, 2017 at 18:21

4 votes

1 answer

313 views

Boundary $\partial F_n$ of a free group $F_n$

asked Mar 3, 2018 at 16:06

3 votes

1 answer

122 views

automorphism of free group $F_n$ fixing $F_{n-1}$ and image of $n$th generator

asked Apr 29, 2018 at 20:01

3 votes

2 answers

102 views

image of homomorphism contains free group, then so does domain

asked May 26, 2018 at 15:07

3 votes

1 answer

363 views

$x_n \to x \in \mathbb{R}$ and $y_n \to 0 $. What about $\frac{x_n}{y_n}$?

asked Jul 13, 2018 at 19:47

3 votes

2 answers

4k views

Why is this function only differentiable at zero?

asked Aug 28, 2018 at 9:36

3 votes

1 answer

109 views

components of subgraph determine subgroups up to conjugacy

asked Mar 17, 2018 at 13:56

3 votes

3 answers

445 views

Prove that $\sum_{k = 0}^{49}(-1)^k\binom{99}{2k} = -2^{49}$

asked Dec 24, 2018 at 17:42

3 votes

0 answers

135 views

showing elements in $\mathbb{Z}+\frac{1 + \sqrt{5}}{2}\mathbb{Z}$ are associated

asked May 15, 2017 at 16:29

3 votes

0 answers

74 views

Factoring $a + b\frac{1 + \sqrt{5}}{2}$ if $a^2 + ab - b^2 = a+b$

asked May 16, 2017 at 14:40

3 votes

2 answers

128 views

Proving that $a+b\sqrt{-3}$ is a cube if $a^2 + 3b^2 = c^3$

asked May 18, 2017 at 9:33

3 votes

1 answer

120 views

Compute $50! \mod 2014$

asked Feb 18, 2017 at 16:50

3 votes

1 answer

438 views

Proof about positive semi-definite matrix

asked Mar 16, 2017 at 10:44

3 votes

2 answers

933 views

Proving $(x_1 - a_1, \ldots, x_n -a_n)$ is a maximal ideal [duplicate]

asked Apr 1, 2017 at 11:28

3 votes

3 answers

145 views

Question about definition of graded ring

asked Apr 3, 2017 at 10:28

3 votes

1 answer

360 views

Non-singular zeros are isolated.

asked Apr 15, 2017 at 11:30

3 votes

4 answers

4k views

Number of elements of order 2

asked Feb 11, 2017 at 10:22

3 votes

3 answers

82 views

Find all couples $(a,b) \in \mathbb{Z}^2$

asked Feb 14, 2017 at 15:10

2 votes

2 answers

469 views

If $m^2 +n^2 - m$ is a multiple of $mn$ and $p$ divides $m$ then $p^2$ divides $m$

asked Feb 15, 2017 at 14:12

2 votes

2 answers

165 views

finding smallest natural number $n$ such that $n \equiv 1023 \bmod 2015$ and $n \equiv 1302 \bmod 2016$

asked Feb 16, 2017 at 11:13

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78 Questions

Pointwise convergence of sequence $(f_n)_n$ of functions to $f$ and changing limits

Supplementary exercise 51, chapter 3 from 'A walk through combinatorics' 4th edition

Tensor product of localization is isomorphic to localization of tensor product

Compute $5!25! \mod 31$

Computing $7^{13} \mod 40$

Inverse image of a Noetherian module under a module morphism

isomorphic extension fields of the $p$-adic numbers

If $x = y^3$ in $\mathbb{Z} + \frac{-1 + \sqrt{-3}}{2}\mathbb{Z}$, then there is some $w \in \mathbb{Z} + \sqrt{-3}\mathbb{Z}$ such that $x = w^3$.

Subgroups of finitely generated group are not necessarily finitely generated (proof).

Restriction of homomorphism to finite index subgroup gives finite index subgroup of kernel

Prove that the following map has at least $k-2$ fixed points

Boundary $\partial F_n$ of a free group $F_n$

automorphism of free group $F_n$ fixing $F_{n-1}$ and image of $n$th generator

image of homomorphism contains free group, then so does domain

$x_n \to x \in \mathbb{R}$ and $y_n \to 0 $. What about $\frac{x_n}{y_n}$?

Why is this function only differentiable at zero?

components of subgraph determine subgroups up to conjugacy

Prove that $\sum_{k = 0}^{49}(-1)^k\binom{99}{2k} = -2^{49}$

showing elements in $\mathbb{Z}+\frac{1 + \sqrt{5}}{2}\mathbb{Z}$ are associated

Factoring $a + b\frac{1 + \sqrt{5}}{2}$ if $a^2 + ab - b^2 = a+b$

Proving that $a+b\sqrt{-3}$ is a cube if $a^2 + 3b^2 = c^3$

Compute $50! \mod 2014$

Proof about positive semi-definite matrix

Proving $(x_1 - a_1, \ldots, x_n -a_n)$ is a maximal ideal [duplicate]

Question about definition of graded ring

Non-singular zeros are isolated.

Number of elements of order 2

Find all couples $(a,b) \in \mathbb{Z}^2$

If $m^2 +n^2 - m$ is a multiple of $mn$ and $p$ divides $m$ then $p^2$ divides $m$

finding smallest natural number $n$ such that $n \equiv 1023 \bmod 2015$ and $n \equiv 1302 \bmod 2016$