Question

An elementary proof of $\pi_1(S^n) =1$ using this general theorem

score 123 · Answer 1 · 2026-03-25 20:42:27

123

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An elementary proof of $\pi_1(S^n) =1$ using this general theorem

Published on 25 Mar 2026 - 20:42

score 546 · Answer 2 · 2026-03-25 23:39:44

546

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Fundamental group of infinite row of circles

Published on 25 Mar 2026 - 23:39

score 29 · Answer 3 · 2018-09-09 17:31:53

Order of nilpotency of ideal generated by kernel of induced map between cohomology rings of 1- dimensional CW complexes

score 1.9k · Answer 4 · 2026-03-25 16:13:38

1.9k

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Showing that a covering map from a path connected space to a simply connected space is a homeomorpism.

Published on 25 Mar 2026 - 16:13

score 64 · Answer 5 · 2026-03-25 12:46:03

64

Views

Sum formulas for Pontrjagin square and Postnikov square

Published on 25 Mar 2026 - 12:46

score 125 · Answer 6 · 2026-03-26 03:08:21

125

Views

Pontryagin square: lifting to an integral cocycle, and an element $H^4 (B^2 \mathbb{Z}_r, \mathbb{Z}_{2r})=$Hom$(\mathbb{Z}_{2r},\mathbb{Z}_{2r})$?

Published on 26 Mar 2026 - 3:08

score 101 · Answer 7 · 2026-03-26 03:02:30

101

Views

Is it there a nice way of visualising $\pi_3(\mathbb{S}^2)$?

Published on 26 Mar 2026 - 3:02

score 59 · Answer 8 · 2026-03-25 08:10:50

59

Views

Is there an algebraic or geometric explanation for why $Spin_7\simeq_{\frac{1}{3}}S^7\times G_2$?

Published on 25 Mar 2026 - 8:10

score 183 · Answer 9 · 2026-03-28 04:33:25

183

Views

Removing countably many points from a manifold

Published on 28 Mar 2026 - 4:33

score 159 · Answer 10 · 2026-03-30 17:56:37

159

Views

Natural isomorphism for a reduced cohomology theory on CW complexes.

Published on 30 Mar 2026 - 17:56

score 248 · Answer 11 · 2026-04-04 02:07:22

248

Views

Singular chain complex as a graded algebra

Published on 04 Apr 2026 - 2:07

score 618 · Answer 12 · 2026-03-25 17:26:00

618

Views

Why do we need affine independence in the definition of a simplex?

Published on 25 Mar 2026 - 17:26

score 25 · Answer 13 · 2026-03-26 03:06:09

25

Views

Covering space in B. O'Neill book, semi-riemannian geom.

Published on 26 Mar 2026 - 3:06

score 209 · Answer 14 · 2018-09-10 21:02:06

209

Views

A topological proof of the Nullhomotopical Cauchy Integral Formula from the Circle Cauchy Integral Formula

Published on 10 Sep 2018 - 21:02

score 41 · Answer 15 · 2026-03-25 11:16:02

41

Views

$\Omega_4^{SO}(K(\mathbb{Z}_2,2))$ v.s. $H^4(K(\mathbb{Z}_2,2),U(1))$: Cocycle form

Published on 25 Mar 2026 - 11:16

List Question

An elementary proof of $\pi_1(S^n) =1$ using this general theorem

Fundamental group of infinite row of circles

Order of nilpotency of ideal generated by kernel of induced map between cohomology rings of 1- dimensional CW complexes

Showing that a covering map from a path connected space to a simply connected space is a homeomorpism.

Sum formulas for Pontrjagin square and Postnikov square

Pontryagin square: lifting to an integral cocycle, and an element $H^4 (B^2 \mathbb{Z}_r, \mathbb{Z}_{2r})=$Hom$(\mathbb{Z}_{2r},\mathbb{Z}_{2r})$?

Is it there a nice way of visualising $\pi_3(\mathbb{S}^2)$?

Is there an algebraic or geometric explanation for why $Spin_7\simeq_{\frac{1}{3}}S^7\times G_2$?

Removing countably many points from a manifold

Natural isomorphism for a reduced cohomology theory on CW complexes.

Singular chain complex as a graded algebra

Why do we need affine independence in the definition of a simplex?

Covering space in B. O'Neill book, semi-riemannian geom.

A topological proof of the Nullhomotopical Cauchy Integral Formula from the Circle Cauchy Integral Formula

$\Omega_4^{SO}(K(\mathbb{Z}_2,2))$ v.s. $H^4(K(\mathbb{Z}_2,2),U(1))$: Cocycle form

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