List questions from homotopy-theory

Published on 13 Apr 2026 - 13:56

91

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Cofiber of inverse limit

Published on 13 Apr 2026 - 7:22

63

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Equivalence between $SP_{h}(X)$ and $\Gamma^{+}(X)$ in simplicial context

Published on 26 Mar 2026 - 3:11

1.3k

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Geometric realization of simplicial sets

Published on 14 Apr 2026 - 18:16

641

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Does $\mathbb R P^n$ retract to $\mathbb R P^k$?

Published on 16 Apr 2026 - 4:07

119

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Yoneda's Lemma and $K(G,n)$

Published on 26 Mar 2026 - 22:31

810

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Understanding the graphic proof of homotopy

Published on 11 Apr 2026 - 14:11

3.4k

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Fundamental group of $\mathbb{R}^2 - \{0\}$

Published on 10 Apr 2026 - 0:57

2.1k

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Every map $S^1 → X$ is homotopic to a constant map$\implies$Every map $S^1 → X$ extends to a map $D^2 → X$.

Published on 16 Apr 2026 - 10:31

1.8k

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Understanding the question of Hatcher 1.1.6

Published on 11 Apr 2026 - 0:52

88

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Is there any precise sense in saying that before Serre the homotopy groups of sphere could in principle have contained an infinite amount of data?

Published on 11 May 2026 - 8:41

1.7k

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How is a doubly twisted cylinder different from a cylinder?

Published on 14 Apr 2026 - 3:21

209

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How to see that this circle is contractible on $S^1\times D^2$?

Published on 13 Apr 2026 - 3:04

53

Views

Question on Stein's book thm. 5.1 (homotopical version of Cauchy's theorem)

Published on 16 Apr 2026 - 4:57

160

Views

Fundamental group of the the union of three planes and $S^2$

Published on 13 Apr 2026 - 17:37

List Question

Nonvanishing vectorfield on $S^n$

Cofiber of inverse limit

Equivalence between $SP_{h}(X)$ and $\Gamma^{+}(X)$ in simplicial context

Geometric realization of simplicial sets

Does $\mathbb R P^n$ retract to $\mathbb R P^k$?

Yoneda's Lemma and $K(G,n)$

Understanding the graphic proof of homotopy

Fundamental group of $\mathbb{R}^2 - \{0\}$

Every map $S^1 → X$ is homotopic to a constant map$\implies$Every map $S^1 → X$ extends to a map $D^2 → X$.

Understanding the question of Hatcher 1.1.6

Is there any precise sense in saying that before Serre the homotopy groups of sphere could in principle have contained an infinite amount of data?

How is a doubly twisted cylinder different from a cylinder?

How to see that this circle is contractible on $S^1\times D^2$?

Question on Stein's book thm. 5.1 (homotopical version of Cauchy's theorem)

Fundamental group of the the union of three planes and $S^2$

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