User Iian Smythe

15 votes

2 answers

676 views

Why do the projections in the Calkin algebra not form a lattice?

asked Jun 17, 2014 at 20:16

14 votes

4 answers

4k views

How much does the absolute value of an operator behave like an absolute value?

asked Jul 8, 2014 at 17:52

11 votes

1 answer

597 views

Approximating a real in the ground model

asked Dec 5, 2020 at 16:13

11 votes

1 answer

332 views

Uncountable homogeneous rectangles for subsets of $\omega_2\times\omega_2$

asked Jul 6, 2021 at 2:12

9 votes

1 answer

310 views

Decidability of the Hilbert lattice and quantum logic

asked Mar 17, 2015 at 15:19

9 votes

1 answer

562 views

Is $\ell^\infty$ Polishable?

asked Jun 11, 2014 at 21:42

9 votes

1 answer

392 views

Nonexistence of generic objects over $L(\mathbb{R})$

asked Apr 24, 2016 at 19:32

9 votes

2 answers

616 views

Extracting subsequences in Banach spaces, along an ultrafilter?

asked Jul 6, 2016 at 17:54

9 votes

1 answer

321 views

Countable $\mathbf\Sigma^1_2$ equivalence relations

asked Mar 16, 2018 at 19:51

8 votes

0 answers

189 views

Examples of analytic $\mathcal{I}$-mad families

asked May 18, 2016 at 15:34

8 votes

1 answer

391 views

Complexity of the set of closed subsets of an analytic set

asked Apr 19, 2019 at 18:08

7 votes

2 answers

670 views

Set of perfect subsets of a Borel set

asked Jul 31, 2019 at 0:44

6 votes

0 answers

72 views

Countable companions for Polish locally compact groups and their orbit equivalence relations

asked Mar 9, 2023 at 22:16

6 votes

1 answer

195 views

Equivalence of questions regarding restrictions of pure states

asked Jun 28, 2016 at 20:02

6 votes

1 answer

394 views

Products and Gale-Stewart games

asked Nov 9, 2017 at 4:18

6 votes

1 answer

300 views

Cohen generics over the ground model still Cohen over other generic extensions?

asked Jul 19, 2018 at 16:18

6 votes

2 answers

467 views

Complete atomless Boolean algebras with abelian automorphism group

asked Aug 25, 2018 at 19:38

6 votes

2 answers

1k views

Characterization of ideals in the bounded operators

asked Jun 20, 2014 at 3:51

6 votes

3 answers

452 views

Can every $\mathcal{L}_{\omega_1,\omega}$ formula be expressed as a type? What about canonical forms?

asked Jun 19, 2012 at 21:24

6 votes

1 answer

275 views

Is the ideal of compact operators strongly Borel?

asked Jun 20, 2013 at 1:47

6 votes

0 answers

333 views

A characterization of Mathias reals

asked Jun 5, 2014 at 0:49

5 votes

0 answers

184 views

The (global) theory of Borel equivalence relations

asked Jul 23, 2014 at 16:56

5 votes

1 answer

431 views

Buying more absoluteness for countable transitive models?

asked Sep 9, 2018 at 20:04

5 votes

2 answers

260 views

Von Neumann's theorem on realizing automorphisms of the measure algebra

asked Jul 6, 2018 at 2:17

5 votes

1 answer

273 views

Is the set of subsequences of branches through a tree Borel?

asked Mar 8, 2016 at 2:33

5 votes

1 answer

151 views

Existence of Borel uniformization for coanalytic set with non-$K_\sigma$ sections

asked Dec 22, 2023 at 18:44

5 votes

1 answer

176 views

Is there a standard Borel space of finitely branching real trees?

asked Nov 9, 2022 at 18:10

4 votes

1 answer

139 views

Is the set of clopen subsets Borel in the Effros Borel space?

asked Aug 3, 2023 at 18:10

4 votes

2 answers

353 views

A property of uncountable almost disjoint families

asked Nov 23, 2015 at 17:18

4 votes

1 answer

180 views

An interpretation for filters of subspaces in Banach spaces

asked Nov 28, 2015 at 21:09

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51 Questions

Why do the projections in the Calkin algebra not form a lattice?

How much does the absolute value of an operator behave like an absolute value?

Approximating a real in the ground model

Uncountable homogeneous rectangles for subsets of $\omega_2\times\omega_2$

Decidability of the Hilbert lattice and quantum logic

Is $\ell^\infty$ Polishable?

Nonexistence of generic objects over $L(\mathbb{R})$

Extracting subsequences in Banach spaces, along an ultrafilter?

Countable $\mathbf\Sigma^1_2$ equivalence relations

Examples of analytic $\mathcal{I}$-mad families

Complexity of the set of closed subsets of an analytic set

Set of perfect subsets of a Borel set

Countable companions for Polish locally compact groups and their orbit equivalence relations

Equivalence of questions regarding restrictions of pure states

Products and Gale-Stewart games

Cohen generics over the ground model still Cohen over other generic extensions?

Complete atomless Boolean algebras with abelian automorphism group

Characterization of ideals in the bounded operators

Can every $\mathcal{L}_{\omega_1,\omega}$ formula be expressed as a type? What about canonical forms?

Is the ideal of compact operators strongly Borel?

A characterization of Mathias reals

The (global) theory of Borel equivalence relations

Buying more absoluteness for countable transitive models?

Von Neumann's theorem on realizing automorphisms of the measure algebra

Is the set of subsequences of branches through a tree Borel?

Existence of Borel uniformization for coanalytic set with non-$K_\sigma$ sections

Is there a standard Borel space of finitely branching real trees?

Is the set of clopen subsets Borel in the Effros Borel space?

A property of uncountable almost disjoint families

An interpretation for filters of subspaces in Banach spaces