Question

Can a group have $\aleph_1$ many subgroups?

score 653 · Answer 1 · 2023-04-04 21:54:58

653

Views

Can a group have $\aleph_1$ many subgroups?

Published on 04 Apr 2023 - 21:54

score 36 · Answer 2 · 2023-04-13 18:28:34

36

Views

Reference for the results of the paper "On a class of probability spaces" by David Blackwell

Published on 13 Apr 2023 - 18:28

score 96 · Answer 3 · 2023-04-17 18:57:47

96

Views

Given any $k\in\Bbb{N}$ there exists $k$ consecutive composite integers such that reciprocal of each composite integer is a Cantor point then $k=1$

Published on 17 Apr 2023 - 18:57

score 149 · Answer 4 · 2023-04-20 07:12:01

149

Views

What exactly is the "$\mathbb{R}$" in $L(\mathbb{R})$?

Published on 20 Apr 2023 - 7:12

score 204 · Answer 5 · 2023-04-27 22:50:45

204

Views

Analytic sets have the Baire property

Published on 27 Apr 2023 - 22:50

score 100 · Answer 6 · 2023-04-29 00:11:16

100

Views

Prove that, in $\mathbb{R}$, $F_\sigma \neq G_\delta$, $F_{\sigma\delta} \neq G_{\delta\sigma}$, etc.

Published on 29 Apr 2023 - 0:11

score 44 · Answer 7 · 2023-05-07 08:00:25

44

Views

What property does an identity relation has?

Published on 07 May 2023 - 8:00

score 161 · Answer 8 · 2023-05-11 01:49:49

161

Views

Is this subset of a closed set Borel measurable?

Published on 11 May 2023 - 1:49

score 127 · Answer 9 · 2023-05-13 20:01:49

127

Views

Is AC invoked in the claim "the product/sum of a sequence of separable metrizable spaces is separable"?

Published on 13 May 2023 - 20:01

score 137 · Answer 10 · 2023-05-14 07:43:15

137

Views

What condition(s) on $X$ and $A$ can ensure the existence of an element $a\in A$ such that $d(x_0, a)=d(x_0, A) $?

Published on 14 May 2023 - 7:43

score 106 · Answer 11 · 2023-05-26 12:37:55

106

Views

Shoenfield absoluteness lemma with just $\mathsf{ZF}$?

Published on 26 May 2023 - 12:37

score 129 · Answer 12 · 2023-05-28 09:57:00

129

Views

Are Borel sets whose projections are Borel closed under intersection?

Published on 28 May 2023 - 9:57

score 25 · Answer 13 · 2023-05-30 18:38:11

25

Views

Why are finite stages of the Borel hierarchy $\bf{\Sigma}^0_n$ closed under bounded quantification?

Published on 30 May 2023 - 18:38

score 61 · Answer 14 · 2023-06-01 11:47:39

61

Views

How does this look like a tree?

Published on 01 Jun 2023 - 11:47

score 72 · Answer 15 · 2023-06-05 04:22:18

72

Views

Is the rank of a tree a natural number or $\omega$?

Published on 05 Jun 2023 - 4:22

List Question

Can a group have $\aleph_1$ many subgroups?

Reference for the results of the paper "On a class of probability spaces" by David Blackwell

Given any $k\in\Bbb{N}$ there exists $k$ consecutive composite integers such that reciprocal of each composite integer is a Cantor point then $k=1$

What exactly is the "$\mathbb{R}$" in $L(\mathbb{R})$?

Analytic sets have the Baire property

Prove that, in $\mathbb{R}$, $F_\sigma \neq G_\delta$, $F_{\sigma\delta} \neq G_{\delta\sigma}$, etc.

What property does an identity relation has?

Is this subset of a closed set Borel measurable?

Is AC invoked in the claim "the product/sum of a sequence of separable metrizable spaces is separable"?

What condition(s) on $X$ and $A$ can ensure the existence of an element $a\in A$ such that $d(x_0, a)=d(x_0, A) $?

Shoenfield absoluteness lemma with just $\mathsf{ZF}$?

Are Borel sets whose projections are Borel closed under intersection?

Why are finite stages of the Borel hierarchy $\bf{\Sigma}^0_n$ closed under bounded quantification?

How does this look like a tree?

Is the rank of a tree a natural number or $\omega$?

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