User Luc Guyot

23 votes

Accepted

Average measure of intersection of a convex region with its translate

answered Oct 7, 2017 at 17:52

20 votes

Accepted

Deciding if $\mathbb{Z}\ltimes_A \mathbb{Z}^5$ and $\mathbb{Z}\ltimes_B \mathbb{Z}^5$ are isomorphic or not

answered Aug 15, 2020 at 16:20

19 votes

Accepted

When is $A\otimes R$ a free $R$-module?

answered Nov 22, 2017 at 7:16

19 votes

Accepted

Has the Jacobson/ Baer radical of a group been studied?

answered Jan 13, 2017 at 23:48

15 votes

Accepted

Finite non-commutative ring with few invertible (unit) elements

answered Oct 29, 2017 at 22:54

14 votes

Accepted

Can one prove the elementary divisor theorem for PIDs by elementary matrix operations?

answered Jul 23, 2017 at 11:01

14 votes

Accepted

Solvable groups that are linear over $\mathbb{C}$ but not over $\mathbb{Q}$?

answered Nov 16, 2023 at 23:50

13 votes

Accepted

What is known about ideal and divisibility lattices of GCD domains and their generalizations?

answered Oct 30, 2017 at 20:46

13 votes

Accepted

Testing whether two elements of $\text{SL}(2, \mathbb{F}_{2^n})$ generate the entire group

answered Oct 25, 2017 at 21:58

13 votes

Accepted

a normal form for matrices over Z[x]/(x^2-1) ?

answered Jun 10, 2016 at 20:34

13 votes

Generators for SL_2(R) for rings of integers R

answered Jun 11, 2016 at 21:06

12 votes

Accepted

Is the product of Jacobson rings a Jacobson ring?

answered May 24, 2018 at 20:38

12 votes

Accepted

Minimum number of relations that must be added to make a group abelian

answered Aug 31, 2019 at 22:05

12 votes

Every subgroup is isomorphic to a normal subgroup

answered Aug 25, 2020 at 19:39

11 votes

Why are finitely generated modules over principal artin local rings direct sums of cyclic modules?

answered Jul 2, 2016 at 21:43

10 votes

When is $SL(n,R) \rightarrow SL(n,R/q)$ surjective?

answered Jun 6, 2016 at 21:21

10 votes

Bass' stable range of $\mathbf Z[X]$

answered Sep 17, 2016 at 12:13

10 votes

Accepted

Does every f.g. group have a minimal presentation?

answered Apr 16, 2020 at 20:39

10 votes

A "simpler" description of the automorphism group of the lamplighter group

answered Jul 13, 2023 at 12:08

10 votes

Commutator subgroup of $\mathrm{GL}_n(R)$ when $R$ is a PID with unity

answered Apr 2 at 21:35

9 votes

Finding prime ideals for ideal classes in arbitrary Dedekind domains

answered Nov 11 at 23:03

9 votes

Accepted

Principal ideal ring, does there exist an invertible matrix such that certain matrix is upper triangular?

answered Sep 30, 2016 at 14:22

9 votes

Accepted

Unique words in dihedral groups

answered Aug 16, 2017 at 23:08

9 votes

For which rings R is SL_n(R) generated by its n-1 fundamental copies of SL_2(R)?

answered Mar 31, 2017 at 22:44

9 votes

$G_n$ 's mutually non-isomorphic

answered Sep 7, 2017 at 19:56

8 votes

For which rings $R$ is $\mathrm{SL}_n(R)$ generated by transvections?

answered Jun 4, 2016 at 17:59

8 votes

Accepted

Intersection of free/affine submodules, comparison with vector spaces

answered Jul 10, 2018 at 0:01

8 votes

Accepted

$R$ a DVR with fraction field $K.$ What are the $R$-submodules of $K^n?$

answered Jun 4, 2018 at 21:46

8 votes

Accepted

Strong approximation for principal ideal domains

answered Dec 4, 2017 at 23:49

8 votes

Accepted

When is countable direct-product of projective modules again projective ?

answered Nov 10, 2017 at 23:17

Stack Exchange Network

110 Answers

Average measure of intersection of a convex region with its translate

Deciding if $\mathbb{Z}\ltimes_A \mathbb{Z}^5$ and $\mathbb{Z}\ltimes_B \mathbb{Z}^5$ are isomorphic or not

When is $A\otimes R$ a free $R$-module?

Has the Jacobson/ Baer radical of a group been studied?

Finite non-commutative ring with few invertible (unit) elements

Can one prove the elementary divisor theorem for PIDs by elementary matrix operations?

Solvable groups that are linear over $\mathbb{C}$ but not over $\mathbb{Q}$?

What is known about ideal and divisibility lattices of GCD domains and their generalizations?

Testing whether two elements of $\text{SL}(2, \mathbb{F}_{2^n})$ generate the entire group

a normal form for matrices over Z[x]/(x^2-1) ?

Generators for SL_2(R) for rings of integers R

Is the product of Jacobson rings a Jacobson ring?

Minimum number of relations that must be added to make a group abelian

Every subgroup is isomorphic to a normal subgroup

Why are finitely generated modules over principal artin local rings direct sums of cyclic modules?

When is $SL(n,R) \rightarrow SL(n,R/q)$ surjective?

Bass' stable range of $\mathbf Z[X]$

Does every f.g. group have a minimal presentation?

A "simpler" description of the automorphism group of the lamplighter group

Commutator subgroup of $\mathrm{GL}_n(R)$ when $R$ is a PID with unity

Finding prime ideals for ideal classes in arbitrary Dedekind domains

Principal ideal ring, does there exist an invertible matrix such that certain matrix is upper triangular?

Unique words in dihedral groups

For which rings R is SL_n(R) generated by its n-1 fundamental copies of SL_2(R)?

$G_n$ 's mutually non-isomorphic

For which rings $R$ is $\mathrm{SL}_n(R)$ generated by transvections?

Intersection of free/affine submodules, comparison with vector spaces

$R$ a DVR with fraction field $K.$ What are the $R$-submodules of $K^n?$

Strong approximation for principal ideal domains

When is countable direct-product of projective modules again projective ?