User Najib Idrissi - Mathematics Stack Exchange

Najib Idrissi

Member for 12 years, 7 months
Last seen this week

GitHub
idrissi.eu
Paris, France

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Answers

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Score Activity Newest

103

How to put 9 pigs into 4 pens so that there are an odd number of pigs in each pen?

Nov 7, 2013

68

Why is $\text{Hom}(V,W)$ the same thing as $V^* \otimes W$?

Feb 17, 2014

48

The "magic diagram" is cartesian

May 2, 2014

46

Square of a second derivative is the fourth derivative

Nov 23, 2015

40

Can this be considered a "rigorous" definition of a limit?

Sep 13, 2016

Questions

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Score Activity Newest Views

52

Have there been (successful) attempts to use something other than spheres for homotopy groups?

Oct 5, 2015

22

When is there a ring structure on an abelian group $(A,+)$?

Jun 30, 2013

16

If $S^1 \hookrightarrow X$ induces an injection of $H_1$, then $X$ retracts onto $S^1$

May 11, 2013

15

Tangent bundle of a quotient by a proper action

Apr 14, 2013

14

Why is the recognition principle important?

Jun 28, 2012

Tags

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algebraic-topology

1,353

Score

312

posts

category-theory

734

Score

154

posts

abstract-algebra

590

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154

posts

general-topology

543

Score

120

posts

homology-cohomology

425

Score

95

posts

Reputation

top 0.43% overall

+10

The relative homology group $H_{1}(\mathbb{R},\mathbb{Q})$

+10

Constant maps induce zero homomorphism

+10

All subgroups normal $\implies$ abelian group

+10

For $n$-degree complex polynomial $p(z) = a_nz^n + \cdots + a_1z + a_0$ defined on $S^2$ is $p$ homotopic to $z^n$?

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algebraic-topology

Jul 2, 2019
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Feb 24, 2016
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Feb 23, 2022

117

silver badges

homology-cohomology

Dec 2, 2022
category-theory

Sep 9, 2016
general-topology

Feb 23, 2019

197

bronze badges

homological-algebra

Feb 27, 2016
homotopy-theory

May 26, 2016
differential-topology

Jan 24, 2018

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