List questions from descriptive-set-theory

Published on 22 Mar 2026 - 16:18

306

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Prove that countable intersection of analytic sets is an analytic set

Published on 17 Mar 2026 - 7:53

153

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Choquet not strong Choquet

Published on 12 Jun 2019 - 22:53

294

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Hierarchy of subsets of $\mathbb{N}$

Published on 17 Jun 2019 - 15:03

296

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Showing that Gale-Stewart Theorem on Determinacy of Open and Closed Games is equivalent to AC

Published on 23 Feb 2026 - 4:42

266

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Covering game in Borel Determinacy proof

Published on 23 Feb 2026 - 4:37

33

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If $\mathcal{J}\subseteq 2^{\omega}$ is a maximal ideal and $D$ is a countable dense subset of $\mathcal{J}$, the closure of $D$ is $2^{\omega}$?

Published on 04 Jul 2019 - 19:57

379

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Cardinality of Perfect Polish Spaces

Published on 22 Mar 2026 - 4:12

103

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Why the Cantor set have $\mathfrak{c}$ subsets homeomorphic to $\mathbb{Q}$?

Published on 10 Jul 2019 - 4:35

104

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If $A$ is $\kappa\text{-Suslin}$ then so is $pA$.

Published on 15 Jul 2019 - 10:47

256

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Hausdorff spaces from filters

Published on 17 Jul 2019 - 21:42

88

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How many analytic sets does the Cantor set have?

Published on 18 Jul 2019 - 20:58

52

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If $A\subseteq{}^\omega2$ is a Borel set, is $\{x\in{}^\omega2\!:(\exists y\in A)\ x\le y\}$ also a Borel set?

Published on 26 Jul 2019 - 12:18

77

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A characterization of the perfect sets in the Cantor set.

Published on 28 Jul 2019 - 4:56

109

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Showing that the property of "being null" is arithmetical.

Published on 28 Jul 2019 - 12:16

List Question

Polish spaces are continuous images of the Baire space

Prove that countable intersection of analytic sets is an analytic set

Choquet not strong Choquet

Hierarchy of subsets of $\mathbb{N}$

Showing that Gale-Stewart Theorem on Determinacy of Open and Closed Games is equivalent to AC

Covering game in Borel Determinacy proof

If $\mathcal{J}\subseteq 2^{\omega}$ is a maximal ideal and $D$ is a countable dense subset of $\mathcal{J}$, the closure of $D$ is $2^{\omega}$?

Cardinality of Perfect Polish Spaces

Why the Cantor set have $\mathfrak{c}$ subsets homeomorphic to $\mathbb{Q}$?

If $A$ is $\kappa\text{-Suslin}$ then so is $pA$.

Hausdorff spaces from filters

How many analytic sets does the Cantor set have?

If $A\subseteq{}^\omega2$ is a Borel set, is $\{x\in{}^\omega2\!:(\exists y\in A)\ x\le y\}$ also a Borel set?

A characterization of the perfect sets in the Cantor set.

Showing that the property of "being null" is arithmetical.

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