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Compactness of intersection of a compact set and an open set

score 1.3k · Answer 1 · 2026-04-11 18:21:17

1.3k

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Compactness of intersection of a compact set and an open set

Published on 11 Apr 2026 - 18:21

score 197 · Answer 2 · 2026-04-13 03:48:55

197

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Detecting Which 3-manifolds are Orientation Double Covers

Published on 13 Apr 2026 - 3:48

score 176 · Answer 3 · 2026-04-14 23:08:28

176

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If $I$ is an interval of $\Bbb{R}$, $f: I \to \Bbb{R}$ connected and $\forall y \in I\; f^{-1}(\{y\})$ closed in $I$ then $f$ is continuous

Published on 14 Apr 2026 - 23:08

score 133 · Answer 4 · 2026-04-09 14:57:39

133

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How to visualize compact space?

Published on 09 Apr 2026 - 14:57

score 252 · Answer 5 · 2026-04-21 13:56:49

252

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Is the Zariski topology on a variety $V$ a maximal Noetherian topology?

Published on 21 Apr 2026 - 13:56

score 40 · Answer 6 · 2026-04-17 13:47:14

40

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Proving a sequence is convergent using continuity of function and the fact the derivative is bounded on a given set..

Published on 17 Apr 2026 - 13:47

score 44 · Answer 7 · 2026-04-15 05:39:02

44

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Proving $(\overline{A})'=A'$ if $(X,\tau)$ for $T_1$.

Published on 15 Apr 2026 - 5:39

score 25 · Answer 8 · 2026-04-16 11:45:47

If a topological space $X$ is locally compact and I have that $x \in C$ for $C$ compact, is there a $U$ of $x$ such that $x \in U \subset C$

score 289 · Answer 9 · 2026-04-13 18:45:19

$X$ is locally compact, Hausdorff, and has a countable family of compact subsets covering $X$, then $X$ is second-countable

score 61 · Answer 10 · 2026-04-08 17:05:20

61

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About the Lindelöf degree of $(R) ^I$

Published on 08 Apr 2026 - 17:05

score 655 · Answer 11 · 2026-04-10 12:31:44

655

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What's the definition of coherent topology in Munkres Topology?

Published on 10 Apr 2026 - 12:31

score 454 · Answer 12 · 2026-04-14 09:58:16

454

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How many ultrafilters there are in an infinite space?

Published on 14 Apr 2026 - 9:58

score 63 · Answer 13 · 2026-04-10 23:54:44

63

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When can I assume that an open interval is an open set in topology?

Published on 10 Apr 2026 - 23:54

score 270 · Answer 14 · 2026-04-13 23:16:02

270

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Topological Properties closed sets

Published on 13 Apr 2026 - 23:16

score 103 · Answer 15 · 2026-04-03 17:33:17

103

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Stone representation of the free $\sigma$-algebra on $\omega_1$ free generators

Published on 03 Apr 2026 - 17:33

List Question

Compactness of intersection of a compact set and an open set

Detecting Which 3-manifolds are Orientation Double Covers

If $I$ is an interval of $\Bbb{R}$, $f: I \to \Bbb{R}$ connected and $\forall y \in I\; f^{-1}(\{y\})$ closed in $I$ then $f$ is continuous

How to visualize compact space?

Is the Zariski topology on a variety $V$ a maximal Noetherian topology?

Proving a sequence is convergent using continuity of function and the fact the derivative is bounded on a given set..

Proving $(\overline{A})'=A'$ if $(X,\tau)$ for $T_1$.

If a topological space $X$ is locally compact and I have that $x \in C$ for $C$ compact, is there a $U$ of $x$ such that $x \in U \subset C$

$X$ is locally compact, Hausdorff, and has a countable family of compact subsets covering $X$, then $X$ is second-countable

About the Lindelöf degree of $(R) ^I$

What's the definition of coherent topology in Munkres Topology?

How many ultrafilters there are in an infinite space?

When can I assume that an open interval is an open set in topology?

Topological Properties closed sets

Stone representation of the free $\sigma$-algebra on $\omega_1$ free generators

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