Question

Is every orientable surface a 2-folded covering of a non-orientable surface?

score 460 · Answer 1 · 2026-03-25 07:43:30

460

Views

Is every orientable surface a 2-folded covering of a non-orientable surface?

Published on 25 Mar 2026 - 7:43

score 145 · Answer 2 · 2026-03-23 00:56:49

145

Views

Showing that a CW complex is compactly generated

Published on 23 Mar 2026 - 0:56

score 92 · Answer 3 · 2026-03-27 12:30:44

92

Views

The given two spaces are homotopic.

Published on 27 Mar 2026 - 12:30

score 142 · Answer 4 · 2026-03-27 15:29:34

142

Views

Universality Theorem for the Universal Cover

Published on 27 Mar 2026 - 15:29

score 1.1k · Answer 5 · 2026-03-23 06:48:53

1.1k

Views

CW complex with fundamental group $\Bbb Z/n$

Published on 23 Mar 2026 - 6:48

score 277 · Answer 6 · 2026-03-22 19:46:21

277

Views

Cohomology and homology of $SU(N)/SO(N)$

Published on 22 Mar 2026 - 19:46

score 208 · Answer 7 · 2026-03-23 00:27:33

208

Views

CW complex definition ambiguity

Published on 23 Mar 2026 - 0:27

score 902 · Answer 8 · 2018-04-01 07:52:39

902

Views

$\mathbb{R}P^n$ in an attaching space construction of CW complex

Published on 01 Apr 2018 - 7:52

score 204 · Answer 9 · 2018-04-01 15:33:34

204

Views

If $A$ is a retract of $X$, then is the (reduced) suspension $SA$ a retract of $SX$?

Published on 01 Apr 2018 - 15:33

score 651 · Answer 10 · 2026-03-28 15:02:58

651

Views

Classifying space of a category / classifying space of a group

Published on 28 Mar 2026 - 15:02

score 286 · Answer 11 · 2018-04-01 23:16:03

286

Views

homology of the union of two circles and a sphere tangent in a point to the two circles

Published on 01 Apr 2018 - 23:16

score 63 · Answer 12 · 2026-03-27 10:12:57

63

Views

Let $E$ be a normed vector space and $f,g: X \rightarrow E-{0}$ are two continuous functions where $\|f(x)-g(x)\| < \|f(x)\|$ for any $x \in X$.

Published on 27 Mar 2026 - 10:12

score 267 · Answer 13 · 2026-03-26 03:47:04

267

Views

Understanding de Rham's theorem.

Published on 26 Mar 2026 - 3:47

score 698 · Answer 14 · 2026-03-26 09:27:01

698

Views

Short exact sequence of functors which splits, but not naturally (revisited, motivated by the Universal Coefficient Theorem)

Published on 26 Mar 2026 - 9:27

score 108 · Answer 15 · 2018-04-03 20:25:34

108

Views

Describing the Kernel of a map from The Fundamental Group to the integers

Published on 03 Apr 2018 - 20:25

List Question

Is every orientable surface a 2-folded covering of a non-orientable surface?

Showing that a CW complex is compactly generated

The given two spaces are homotopic.

Universality Theorem for the Universal Cover

CW complex with fundamental group $\Bbb Z/n$

Cohomology and homology of $SU(N)/SO(N)$

CW complex definition ambiguity

$\mathbb{R}P^n$ in an attaching space construction of CW complex

If $A$ is a retract of $X$, then is the (reduced) suspension $SA$ a retract of $SX$?

Classifying space of a category / classifying space of a group

homology of the union of two circles and a sphere tangent in a point to the two circles

Let $E$ be a normed vector space and $f,g: X \rightarrow E-{0}$ are two continuous functions where $\|f(x)-g(x)\| < \|f(x)\|$ for any $x \in X$.

Understanding de Rham's theorem.

Short exact sequence of functors which splits, but not naturally (revisited, motivated by the Universal Coefficient Theorem)

Describing the Kernel of a map from The Fundamental Group to the integers

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