User Arnaud D.

4 votes

Accepted

Can there be more than one natural transformation between two functors?

answered Mar 21, 2017 at 10:44

4 votes

Understanding Mac Lane's definition of a Functor Representation

answered Mar 22, 2017 at 9:51

4 votes

Accepted

If a linear isometry is injective on a subset of $\mathbb R^n$, is it also surjective?

answered Feb 25, 2017 at 20:52

4 votes

Minimal polynomial for T is a product of distinct linear factors

answered Nov 27, 2017 at 10:21

4 votes

Accepted

Show that is not possible to form a unity ring structure on $(\Bbb Q /\Bbb Z , + )$

answered May 2, 2017 at 16:11

4 votes

Accepted

Prove that bilinear form can be presented as product of linear forms if and only if it has rank one

answered Jun 3, 2017 at 16:27

4 votes

Accepted

Group and subgroups problem

answered May 29, 2017 at 10:36

4 votes

Accepted

Are $\langle X-1\rangle $ and $\langle X+1\rangle $ comaximal in $\Bbb Z[X]$?

answered Jun 17, 2017 at 11:27

4 votes

Accepted

trace inequality for positive semidefinite matrix

answered Jun 12, 2017 at 10:20

4 votes

Accepted

Proving adjoint functors preserve limits by lifting the adjunction to cone categories

answered Aug 1, 2017 at 9:42

4 votes

Accepted

The induced morphism $B/A\to C/A$ is monic/epi if the morphism $B \to C$ is monic/epi in abelian categories

answered Jul 11, 2017 at 16:41

4 votes

Accepted

If $G$ is of order $n$ and $k$ is prime to $n$ then $g(x)=x^k$ is one-to-one

answered Feb 1, 2016 at 11:31

4 votes

If $Gal(G_f)=S_n$ then show that $Aut(\alpha)$ is trivial

answered Nov 7, 2015 at 14:34

4 votes

Accepted

Let $S:U\rightarrow V, \ T:V\rightarrow W$ and if $S$ and $T$ are both injective/surjective, is $T\circ S$ injective/surjective?

answered Mar 1, 2016 at 16:18

4 votes

Let $G ⊂ S_7$ be a subgroup of order 8. Then there exists $i$ such that $\sigma(i)=i.$

answered Mar 23, 2016 at 16:59

4 votes

Accepted

What is the smallest $m>0$ for the Frobenius automorhism of a Galois Field to be the identity?

answered Mar 28, 2016 at 12:49

4 votes

Prove $u\left( x\right)=W\left( x\right)+W'\left( x\right)+W''\left( x\right)+ \cdots \ge 0.$

answered Mar 29, 2016 at 12:53

4 votes

Accepted

Is $\mathbb Q(\sqrt{4+i\sqrt{20}},\sqrt{4-i\sqrt{20}})=\mathbb Q (\sqrt{4+i\sqrt{20}})$?

answered May 28, 2016 at 19:57

4 votes

Accepted

In how many ways can you select a committee of 3 persons, so that no two are from the same department?

answered Jun 11, 2016 at 14:07

4 votes

Accepted

Index of intersection of two normal subgroups

answered Jun 16, 2016 at 8:54

4 votes

Accepted

Proof of a statement about eigenvalues and eigenvectors.

answered Jun 5, 2016 at 13:57

4 votes

Accepted

Shaw that $T(f)(x)=\int_0^x f(s)(1+s^2)ds$ is not surjective.

answered Jul 3, 2016 at 12:02

4 votes

Accepted

Prove the inequality $\frac{ab}c+\frac{ac}b+\frac{bc}a\ge a^2+b^2+c^2-abc+1$

answered Sep 15, 2016 at 14:03

4 votes

Accepted

Is $B \otimes_A M$ a free $B$ module if $M$ is a free $A$ module?

answered Apr 25, 2019 at 12:16

4 votes

On group quotient by a characteristic subgroup

answered Jun 19, 2019 at 9:37

4 votes

Accepted

About noetherian commutative rings

answered Jul 2, 2019 at 10:36

4 votes

Accepted

Proving the Splitting Lemma on pg.147 in AT.

answered Nov 20, 2019 at 10:07

4 votes

Accepted

Schur's Lemma and $Z(G)$

answered Oct 31, 2018 at 9:43

4 votes

Constructing limits in an additive category given the existence of products and kernels

answered Sep 13, 2018 at 14:47

4 votes

Accepted

Left adjoint of evaluation functor

answered Sep 4, 2018 at 9:39

Stack Exchange Network

534 Answers

Can there be more than one natural transformation between two functors?

Understanding Mac Lane's definition of a Functor Representation

If a linear isometry is injective on a subset of $\mathbb R^n$, is it also surjective?

Minimal polynomial for T is a product of distinct linear factors

Show that is not possible to form a unity ring structure on $(\Bbb Q /\Bbb Z , + )$

Prove that bilinear form can be presented as product of linear forms if and only if it has rank one

Group and subgroups problem

Are $\langle X-1\rangle $ and $\langle X+1\rangle $ comaximal in $\Bbb Z[X]$?

trace inequality for positive semidefinite matrix

Proving adjoint functors preserve limits by lifting the adjunction to cone categories

The induced morphism $B/A\to C/A$ is monic/epi if the morphism $B \to C$ is monic/epi in abelian categories

If $G$ is of order $n$ and $k$ is prime to $n$ then $g(x)=x^k$ is one-to-one

If $Gal(G_f)=S_n$ then show that $Aut(\alpha)$ is trivial

Let $S:U\rightarrow V, \ T:V\rightarrow W$ and if $S$ and $T$ are both injective/surjective, is $T\circ S$ injective/surjective?

Let $G ⊂ S_7$ be a subgroup of order 8. Then there exists $i$ such that $\sigma(i)=i.$

What is the smallest $m>0$ for the Frobenius automorhism of a Galois Field to be the identity?

Prove $u\left( x\right)=W\left( x\right)+W'\left( x\right)+W''\left( x\right)+ \cdots \ge 0.$

Is $\mathbb Q(\sqrt{4+i\sqrt{20}},\sqrt{4-i\sqrt{20}})=\mathbb Q (\sqrt{4+i\sqrt{20}})$?

In how many ways can you select a committee of 3 persons, so that no two are from the same department?

Index of intersection of two normal subgroups

Proof of a statement about eigenvalues and eigenvectors.

Shaw that $T(f)(x)=\int_0^x f(s)(1+s^2)ds$ is not surjective.

Prove the inequality $\frac{ab}c+\frac{ac}b+\frac{bc}a\ge a^2+b^2+c^2-abc+1$

Is $B \otimes_A M$ a free $B$ module if $M$ is a free $A$ module?

On group quotient by a characteristic subgroup

About noetherian commutative rings

Proving the Splitting Lemma on pg.147 in AT.

Schur's Lemma and $Z(G)$

Constructing limits in an additive category given the existence of products and kernels

Left adjoint of evaluation functor