Question

Contractible subset of $\mathbb{R}^N$ that is not a deformation retract

score 320 · Answer 1 · 2026-04-10 16:51:15

320

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Contractible subset of $\mathbb{R}^N$ that is not a deformation retract

Published on 10 Apr 2026 - 16:51

score 1.6k · Answer 2 · 2020-02-15 17:52:38

1.6k

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Neighborhood deformation retracts vs cofibrations

Published on 15 Feb 2020 - 17:52

score 148 · Answer 3 · 2026-04-11 05:43:39

148

Views

Homotopy class of path and fundamental group

Published on 11 Apr 2026 - 5:43

score 125 · Answer 4 · 2026-03-25 11:03:15

125

Views

How do I prove that all smooth manifolds being homotopic implies contractible?

Published on 25 Mar 2026 - 11:03

score 93 · Answer 5 · 2026-04-15 13:24:29

93

Views

Filling a map $X\times\Lambda^n_k\rightarrow Y$ to a map $X\times\Delta^n\rightarrow Y$

Published on 15 Apr 2026 - 13:24

score 195 · Answer 6 · 2026-03-25 17:51:50

195

Views

Computing $\pi_4(SU(3))$ using Serre spectral sequence

Published on 25 Mar 2026 - 17:51

score 207 · Answer 7 · 2026-04-16 05:57:16

207

Views

Let $S^1 = \{ (x,y) \in \mathbb R^2 : x^2 + y^2 = 1 \}$ and let $A = \{(0,-1), (0,1)\}$ and let $B = A \cup \{(1,0)\}$

Published on 16 Apr 2026 - 5:57

score 138 · Answer 8 · 2026-04-09 00:36:19

138

Views

What are cohomotopy applications?

Published on 09 Apr 2026 - 0:36

score 147 · Answer 9 · 2026-04-16 19:41:17

147

Views

Is this the right way to construct the adjunction space homotopy equivalent to $S^1$? If not, then how to do it?

Published on 16 Apr 2026 - 19:41

score 285 · Answer 10 · 2026-04-14 17:13:06

285

Views

Cell structure of sphere with 3 points identified

Published on 14 Apr 2026 - 17:13

score 258 · Answer 11 · 2026-04-11 17:46:09

258

Views

Bijection between basepoint-preserving homotopy classes and homomorphism between homological groups

Published on 11 Apr 2026 - 17:46

score 644 · Answer 12 · 2026-04-12 10:41:00

644

Views

Is a solid sphere with a "bubble" in the middle topologically the same as a torus?

Published on 12 Apr 2026 - 10:41

score 135 · Answer 13 · 2026-04-13 19:53:56

135

Views

p-adic Pontryagin class invariance

Published on 13 Apr 2026 - 19:53

score 229 · Answer 14 · 2026-04-09 07:13:28

229

Views

Homology is homotopy invariant, fake proof with simplicial methods?

Published on 09 Apr 2026 - 7:13

score 332 · Answer 15 · 2026-04-13 17:10:03

332

Views

Tammo tom Dieck's Algebraic Topology - van Kampen theorem for groupoids

Published on 13 Apr 2026 - 17:10

List Question

Contractible subset of $\mathbb{R}^N$ that is not a deformation retract

Neighborhood deformation retracts vs cofibrations

Homotopy class of path and fundamental group

How do I prove that all smooth manifolds being homotopic implies contractible?

Filling a map $X\times\Lambda^n_k\rightarrow Y$ to a map $X\times\Delta^n\rightarrow Y$

Computing $\pi_4(SU(3))$ using Serre spectral sequence

Let $S^1 = \{ (x,y) \in \mathbb R^2 : x^2 + y^2 = 1 \}$ and let $A = \{(0,-1), (0,1)\}$ and let $B = A \cup \{(1,0)\}$

What are cohomotopy applications?

Is this the right way to construct the adjunction space homotopy equivalent to $S^1$? If not, then how to do it?

Cell structure of sphere with 3 points identified

Bijection between basepoint-preserving homotopy classes and homomorphism between homological groups

Is a solid sphere with a "bubble" in the middle topologically the same as a torus?

p-adic Pontryagin class invariance

Homology is homotopy invariant, fake proof with simplicial methods?

Tammo tom Dieck's Algebraic Topology - van Kampen theorem for groupoids

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