User Arbutus

16 votes

Visually stunning math concepts which are easy to explain

answered Jun 28, 2018 at 2:56

7 votes

Retraction of the Möbius strip to its boundary

answered Jan 10, 2019 at 4:06

4 votes

Is there a direct, elementary proof of $n = \sum_{k|n} \phi(k)$?

answered Jan 20, 2018 at 14:46

4 votes

Accepted

What is the trace of the algebraic element?

answered May 26, 2018 at 1:38

4 votes

Question on Iwasawa Theory

answered Oct 23, 2020 at 12:23

4 votes

Why is the residue field of $\mathbb{Q}_p$ isomorphic to $\mathbb{F}_p$?

answered Feb 21, 2019 at 0:04

3 votes

Why do mathematicians understand structure preservation in a such a way?

answered Mar 16, 2018 at 21:16

3 votes

Accepted

Existence of $\mathbb{Q}$ isomorphism

answered Mar 19, 2021 at 0:17

2 votes

Number of embeddings in algebraic closure

answered May 16, 2018 at 3:43

2 votes

Is the minimal number of generators of an ideal the rank of the ideal as a free $\mathbb Z$-module?

answered Sep 5, 2015 at 19:06

2 votes

Category of vector spaces and matrices

answered May 27, 2018 at 15:48

2 votes

Book recommendations for Geometry

answered Jul 4, 2018 at 20:30

1 vote

Learning to use MAGMA

answered Jul 22, 2020 at 16:26

1 vote

Why is the image of a $\pmod p$ Galois representation finite?

answered Apr 29, 2020 at 14:44

1 vote

Accepted

Issue with Hartshorne definition of finite morphism?

answered Jun 13, 2020 at 16:26

1 vote

Stabilizer of a doubly transitive is maximal?

answered Jun 19, 2018 at 21:14

1 vote

LMFDB labeling of Dirichlet characters

answered Feb 14, 2022 at 23:02

0 votes

Accepted

Proving upper ramification groups are open

answered Apr 13, 2017 at 17:28

0 votes

$T$-invariant subspaces, where the characteristic polynomial of $T$ is $x^4-3x^3$

answered Jan 13, 2018 at 18:16

0 votes

A transitive subgroup of $S_n$ containing a p-cycle with $\frac n2<p<n-2$ is $S_n$ or $A_n$

answered Feb 28, 2019 at 15:44

Stack Exchange Network

20 Answers

Visually stunning math concepts which are easy to explain

Retraction of the Möbius strip to its boundary

Is there a direct, elementary proof of $n = \sum_{k|n} \phi(k)$?

What is the trace of the algebraic element?

Question on Iwasawa Theory

Why is the residue field of $\mathbb{Q}_p$ isomorphic to $\mathbb{F}_p$?

Why do mathematicians understand structure preservation in a such a way?

Existence of $\mathbb{Q}$ isomorphism

Number of embeddings in algebraic closure

Is the minimal number of generators of an ideal the rank of the ideal as a free $\mathbb Z$-module?

Category of vector spaces and matrices

Book recommendations for Geometry

Learning to use MAGMA

Why is the image of a $\pmod p$ Galois representation finite?

Issue with Hartshorne definition of finite morphism?

Stabilizer of a doubly transitive is maximal?

LMFDB labeling of Dirichlet characters

Proving upper ramification groups are open

$T$-invariant subspaces, where the characteristic polynomial of $T$ is $x^4-3x^3$

A transitive subgroup of $S_n$ containing a p-cycle with $\frac n2<p<n-2$ is $S_n$ or $A_n$