Question

Is the colimit of an expanding sequence of $T_4$ spaces $T_4$?

score 78 · Answer 1 · 2020-08-02 19:58:08

78

Views

Is the colimit of an expanding sequence of $T_4$ spaces $T_4$?

Published on 02 Aug 2020 - 19:58

score 92 · Answer 2 · 2020-08-08 00:22:32

92

Views

Infinite connected Hausdorff

Published on 08 Aug 2020 - 0:22

score 164 · Answer 3 · 2026-02-23 02:45:29

164

Views

Continuum cannot be written as Countable Union of Disjoint Closed Subsets

Published on 23 Feb 2026 - 2:45

score 28 · Answer 4 · 2020-08-12 12:56:52

28

Views

Base Characterization of Tychonoff Spaces

Published on 12 Aug 2020 - 12:56

score 30 · Answer 5 · 2020-08-15 13:00:02

30

Views

Existence of Countable Non-Closed set in an Infinite Completely Normal space

Published on 15 Aug 2020 - 13:00

score 278 · Answer 6 · 2020-09-06 00:50:45

278

Views

A regular space has an infinite family composed by disjoint open sets.

Published on 06 Sep 2020 - 0:50

score 72 · Answer 7 · 2020-09-12 14:17:45

72

Views

What axiom of separation is needed here?

Published on 12 Sep 2020 - 14:17

score 175 · Answer 8 · 2020-09-22 18:43:19

175

Views

Showing that a set is closed if $Y$ is Hausdorff

Published on 22 Sep 2020 - 18:43

score 284 · Answer 9 · 2020-09-23 23:58:24

284

Views

If $(X, \tau)$ is $T_1$ and there is an open-closed set basis for the $X$ topology, show that $X$ is completely regular.

Published on 23 Sep 2020 - 23:58

score 626 · Answer 10 · 2020-09-27 14:44:55

626

Views

Why is this quotient of the punctured plane not Hausdorff (Hatcher 1.3.25)?

Published on 27 Sep 2020 - 14:44

score 340 · Answer 11 · 2020-09-28 20:13:20

340

Views

What topological properties are trivially/vacuously satisfied by any indiscrete space?

Published on 28 Sep 2020 - 20:13

score 163 · Answer 12 · 2020-10-06 02:24:49

163

Views

Does there exists a non-Hausdorff topological vector space with a proper convex open subset?

Published on 06 Oct 2020 - 2:24

score 417 · Answer 13 · 2026-03-26 17:52:28

417

Views

$\mathbb{R}^n$ with the Zariski topology is not $T_2$

Published on 26 Mar 2026 - 17:52

score 340 · Answer 14 · 2020-10-11 19:04:10

340

Views

Understanding CW Complexes and proving they are Hausdorff

Published on 11 Oct 2020 - 19:04

score 61 · Answer 15 · 2020-10-13 22:32:24

61

Views

Countable Regular Spaces Which Are Not Monotonically Normal

Published on 13 Oct 2020 - 22:32

List Question

Is the colimit of an expanding sequence of $T_4$ spaces $T_4$?

Infinite connected Hausdorff

Continuum cannot be written as Countable Union of Disjoint Closed Subsets

Base Characterization of Tychonoff Spaces

Existence of Countable Non-Closed set in an Infinite Completely Normal space

A regular space has an infinite family composed by disjoint open sets.

What axiom of separation is needed here?

Showing that a set is closed if $Y$ is Hausdorff

If $(X, \tau)$ is $T_1$ and there is an open-closed set basis for the $X$ topology, show that $X$ is completely regular.

Why is this quotient of the punctured plane not Hausdorff (Hatcher 1.3.25)?

What topological properties are trivially/vacuously satisfied by any indiscrete space?

Does there exists a non-Hausdorff topological vector space with a proper convex open subset?

$\mathbb{R}^n$ with the Zariski topology is not $T_2$

Understanding CW Complexes and proving they are Hausdorff

Countable Regular Spaces Which Are Not Monotonically Normal

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