User Frank - Mathematics Stack Exchange

36 votes

3 answers

1k views

Simple results that are clarified by abstract algebra

asked Dec 23, 2022 at 22:05

6 votes

0 answers

221 views

How did Évariste Galois discover Galois theory?

asked Jul 31, 2023 at 5:36

5 votes

1 answer

132 views

Are these normed vector spaces homeomorphic?

asked Aug 26, 2022 at 22:22

5 votes

3 answers

189 views

Visual proof for $\frac{a}{b} + \frac{c}{d} = \frac{ad + bc}{bd}$

asked Jan 31, 2021 at 23:33

5 votes

2 answers

155 views

Prove that $(b - a)^p \leq b^p - a^p$ when $0 \leq a \leq b$ and $p \geq 1$

asked Dec 20, 2021 at 1:10

5 votes

2 answers

330 views

Interchanging spatial Fourier transform and time derivative for heat kernel

asked Apr 23, 2022 at 17:54

4 votes

1 answer

141 views

Prove that a non-decreasing function has zero derivative

asked Aug 10, 2021 at 5:11

4 votes

0 answers

83 views

Relation between extension of scalars and restriction of scalars

asked Nov 20, 2022 at 23:49

3 votes

1 answer

76 views

Pullback of a good pair by a fibration

asked Nov 28, 2023 at 21:47

3 votes

2 answers

73 views

Applying Fourier transforms in two variables separately

asked May 7, 2022 at 7:05

3 votes

1 answer

133 views

What's the intuition behind $T^*T$?

asked Dec 13, 2020 at 0:37

3 votes

0 answers

57 views

What exactly is $T^2f$?

asked Dec 12, 2023 at 6:32

2 votes

0 answers

30 views

Prove that an edge in planar graph cannot belong to three faces using the Jordan curve theorem

asked Apr 21, 2022 at 18:57

2 votes

1 answer

168 views

Intuition for coboundaries

asked Jun 4, 2023 at 21:49

2 votes

1 answer

214 views

Lifting triangulation by branched covering map

asked Feb 23, 2023 at 21:18

2 votes

1 answer

125 views

Functor from orbit category to Top

asked Oct 14, 2022 at 1:40

2 votes

0 answers

55 views

Every smooth function on $\mathbb{R}^2 \setminus \{0\}$ is the curl of some vector field [duplicate]

asked Nov 7, 2022 at 3:01

1 vote

1 answer

75 views

Uniqueness of adjoining a root to an integral domain

asked Nov 20, 2022 at 8:42

1 vote

0 answers

371 views

Proof that torsion-free module over a PID is flat

asked Oct 30, 2022 at 21:15

1 vote

1 answer

190 views

Exercise 2.25 in Atiyah & Macdonald

asked Dec 20, 2022 at 3:10

1 vote

1 answer

52 views

What does the "$k$-th tangent mapping" refer to?

asked Dec 12, 2023 at 2:33

1 vote

0 answers

55 views

Proving the Grassmannian is a manifold

asked Sep 16, 2023 at 14:43

1 vote

0 answers

112 views

Generators of the fundamental group of a graph

asked Apr 30, 2023 at 0:06

1 vote

1 answer

55 views

Is the isomorphism $H_n(S^n) \cong H_n(U, U - x)$ "natural"?

asked May 21, 2023 at 1:51

1 vote

1 answer

190 views

Closure of simply connected set in $\mathbb{C}$ with smooth boundary is path-connected

asked Jun 3, 2021 at 8:16

1 vote

0 answers

203 views

Proving that linear isometries preserve angles without the polarization identity

asked Jun 26, 2021 at 22:27

1 vote

0 answers

52 views

Is polynomial coefficient map continuous?

asked Sep 8, 2021 at 23:02

1 vote

1 answer

317 views

Understanding the normalizer of a Sylow $p$-subgroup

asked Nov 27, 2021 at 5:36

1 vote

1 answer

82 views

Fixed point of holomorphic map has a constant multiplier

asked Dec 7, 2021 at 8:18

1 vote

0 answers

60 views

Uniqueness of Poincaré metric on disk

asked May 1 at 14:33

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45 Questions

Simple results that are clarified by abstract algebra

How did Évariste Galois discover Galois theory?

Are these normed vector spaces homeomorphic?

Visual proof for $\frac{a}{b} + \frac{c}{d} = \frac{ad + bc}{bd}$

Prove that $(b - a)^p \leq b^p - a^p$ when $0 \leq a \leq b$ and $p \geq 1$

Interchanging spatial Fourier transform and time derivative for heat kernel

Prove that a non-decreasing function has zero derivative

Relation between extension of scalars and restriction of scalars

Pullback of a good pair by a fibration

Applying Fourier transforms in two variables separately

What's the intuition behind $T^*T$?

What exactly is $T^2f$?

Prove that an edge in planar graph cannot belong to three faces using the Jordan curve theorem

Intuition for coboundaries

Lifting triangulation by branched covering map

Functor from orbit category to Top

Every smooth function on $\mathbb{R}^2 \setminus \{0\}$ is the curl of some vector field [duplicate]

Uniqueness of adjoining a root to an integral domain

Proof that torsion-free module over a PID is flat

Exercise 2.25 in Atiyah & Macdonald

What does the "$k$-th tangent mapping" refer to?

Proving the Grassmannian is a manifold

Generators of the fundamental group of a graph

Is the isomorphism $H_n(S^n) \cong H_n(U, U - x)$ "natural"?

Closure of simply connected set in $\mathbb{C}$ with smooth boundary is path-connected

Proving that linear isometries preserve angles without the polarization identity

Is polynomial coefficient map continuous?

Understanding the normalizer of a Sylow $p$-subgroup

Fixed point of holomorphic map has a constant multiplier

Uniqueness of Poincaré metric on disk