User Alexei Averchenko

112 votes

4 answers

27k views

Why do we define quotient groups for normal subgroups only?

asked Dec 14, 2010 at 11:54

43 votes

3 answers

1k views

How do I find partners for study?

asked Jan 15, 2012 at 6:32

36 votes

3 answers

11k views

Is there a continuous bijection from $\mathbb{R}$ to $\mathbb{R}^2$

asked Jun 25, 2011 at 6:54

30 votes

3 answers

8k views

A ring element with a left inverse but no right inverse?

asked Oct 8, 2011 at 3:25

21 votes

1 answer

721 views

Is there a way to make tangent bundle a monad?

asked Nov 20, 2011 at 11:41

17 votes

3 answers

5k views

A commutative ring $A$ is a field iff $A[x]$ is a PID

asked Apr 10, 2013 at 8:47

15 votes

1 answer

2k views

An example of a derivation at a point on a $C^k$-manifold which is not a tangent vector

asked Oct 18, 2011 at 15:52

15 votes

8 answers

5k views

What's the thing with $\sqrt{-1} = i$

asked Dec 10, 2010 at 13:25

13 votes

1 answer

2k views

Equivalence relation on a proper class

asked Feb 27, 2011 at 15:27

12 votes

1 answer

898 views

Categorification of characteristic polynomial

asked Aug 15, 2011 at 18:49

11 votes

4 answers

2k views

What does "working mathematician" mean?

asked Nov 25, 2012 at 23:40

10 votes

1 answer

514 views

Is $\mathbf{Grp}$ a concrete category?

asked Dec 12, 2010 at 11:52

10 votes

5 answers

4k views

How to prove that $\mathbb{Q} \subset \mathbb{R}$ is not locally compact directly?

asked Jul 6, 2011 at 4:17

9 votes

2 answers

973 views

Can we say that $V \cong V^*$ is not natural?

asked Mar 13, 2011 at 9:44

8 votes

1 answer

1k views

How to check the veracity of arXiv.org papers?

asked Jan 24, 2011 at 16:11

8 votes

3 answers

2k views

Introduction to Bourbaki structures, and their relation to category theory

asked Mar 8, 2011 at 12:34

8 votes

2 answers

456 views

What's bad about left $\mathbb{H}$-modules?

asked Sep 2, 2011 at 22:20

8 votes

1 answer

393 views

Finding 'verbally smallest' element of a finitely generated group

asked Nov 8, 2011 at 15:32

8 votes

0 answers

398 views

When is a free and transitive $G$-space homeomorphic to $G$? And when is it (not) a torsor?

asked Sep 22, 2011 at 11:22

8 votes

1 answer

912 views

Do pushouts preserve regular monomorphisms?

asked Dec 2, 2012 at 12:38

7 votes

1 answer

308 views

'Quantum' approach to classical probability

asked Aug 11, 2012 at 4:50

7 votes

1 answer

659 views

Uniqueness of the derivative in locally convex topological vector space

asked Jul 16, 2011 at 12:12

6 votes

1 answer

5k views

What is the dimension of a representation

asked Apr 10, 2011 at 13:03

6 votes

1 answer

1k views

Levi-Civita connection of a left-invariant metric

asked Apr 22, 2011 at 0:06

6 votes

0 answers

281 views

An exercise in Serre's Lie algebra book

asked May 24, 2012 at 11:23

6 votes

1 answer

912 views

Principal and fiber bundles as defined by Husemoller

asked Sep 10, 2011 at 4:06

5 votes

1 answer

892 views

Construction of the morphism from the zig-zag lemma

asked Aug 17, 2011 at 12:39

5 votes

0 answers

482 views

Differential geometry text with categorial flavor

asked Sep 30, 2011 at 14:51

5 votes

4 answers

7k views

Need a hint: prove that $[0, 1]$ and $(0, 1)$ are not homeomorphic

asked Jun 5, 2011 at 11:45

5 votes

3 answers

284 views

Motivating differentiable manifolds

asked Feb 5, 2011 at 23:53

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84 Questions

Why do we define quotient groups for normal subgroups only?

How do I find partners for study?

Is there a continuous bijection from $\mathbb{R}$ to $\mathbb{R}^2$

A ring element with a left inverse but no right inverse?

Is there a way to make tangent bundle a monad?

A commutative ring $A$ is a field iff $A[x]$ is a PID

An example of a derivation at a point on a $C^k$-manifold which is not a tangent vector

What's the thing with $\sqrt{-1} = i$

Equivalence relation on a proper class

Categorification of characteristic polynomial

What does "working mathematician" mean?

Is $\mathbf{Grp}$ a concrete category?

How to prove that $\mathbb{Q} \subset \mathbb{R}$ is not locally compact directly?

Can we say that $V \cong V^*$ is not natural?

How to check the veracity of arXiv.org papers?

Introduction to Bourbaki structures, and their relation to category theory

What's bad about left $\mathbb{H}$-modules?

Finding 'verbally smallest' element of a finitely generated group

When is a free and transitive $G$-space homeomorphic to $G$? And when is it (not) a torsor?

Do pushouts preserve regular monomorphisms?

'Quantum' approach to classical probability

Uniqueness of the derivative in locally convex topological vector space

What is the dimension of a representation

Levi-Civita connection of a left-invariant metric

An exercise in Serre's Lie algebra book

Principal and fiber bundles as defined by Husemoller

Construction of the morphism from the zig-zag lemma

Differential geometry text with categorial flavor

Need a hint: prove that $[0, 1]$ and $(0, 1)$ are not homeomorphic

Motivating differentiable manifolds