Question

Given an ordinal with a particular cofinality, can we find other cofinal subsets with order type and cofinality at least that large?

score 201 · Answer 1 · 2026-04-16 11:17:00

201

Views

Given an ordinal with a particular cofinality, can we find other cofinal subsets with order type and cofinality at least that large?

Published on 16 Apr 2026 - 11:17

score 95 · Answer 2 · 2026-04-18 02:59:10

Iterated forcing and non-existance of a model $N$ such that $\langle G_n : n \in \omega \rangle \in N$ and $\text{o}(N) = \text{o}(M)$.

score 942 · Answer 3 · 2026-04-11 04:00:16

942

Views

Existence of Natural Numbers as an Axiom

Published on 11 Apr 2026 - 4:00

score 167 · Answer 4 · 2026-04-20 09:03:00

167

Views

What does a hyperreal version of the Cantor Set look like?

Published on 20 Apr 2026 - 9:03

score 216 · Answer 5 · 2026-04-12 06:08:01

216

Views

Sets definable by $\Sigma_2$ parameters

Published on 12 Apr 2026 - 6:08

score 130 · Answer 6 · 2026-04-08 17:49:56

130

Views

Von Neumann integers definition

Published on 08 Apr 2026 - 17:49

score 43 · Answer 7 · 2026-04-11 16:17:51

43

Views

Regularity Enforces Trivial $\in$-Isomorphisms

Published on 11 Apr 2026 - 16:17

score 138 · Answer 8 · 2026-04-14 23:11:13

138

Views

If $\subseteq$ is defined set-theoretically, it doesn't exist

Published on 14 Apr 2026 - 23:11

score 53 · Answer 9 · 2026-04-15 07:29:40

53

Views

Show the cardinality of the infinite union of sets is less than the cardinality of the Cartesian product of those sets.

Published on 15 Apr 2026 - 7:29

score 311 · Answer 10 · 2026-04-17 09:28:38

Is it possible to base the slow-growing hierarchy on the ordinal defined as “the height of the minimal model of ZFC (assuming it exists)”?

score 125 · Answer 11 · 2026-04-09 22:41:48

125

Views

How can axiomatic set theory handle real-life objects?

Published on 09 Apr 2026 - 22:41

score 132 · Answer 12 · 2026-04-13 01:20:36

132

Views

Is there a way to prove the Banach-Tarski theorem from just the Partition Principle?

Published on 13 Apr 2026 - 1:20

score 70 · Answer 13 · 2026-04-16 22:27:58

70

Views

Absent choice, if $A$ and $B$ have a bijection, must every surjective function from $A$ to $B$ have a right inverse?

Published on 16 Apr 2026 - 22:27

score 268 · Answer 14 · 2026-04-13 05:38:37

268

Views

How do set theorists view this issue?

Published on 13 Apr 2026 - 5:38

score 243 · Answer 15 · 2026-04-16 12:09:01

243

Views

Are there countably many numbers than can be described?

Published on 16 Apr 2026 - 12:09

List Question

Given an ordinal with a particular cofinality, can we find other cofinal subsets with order type and cofinality at least that large?

Iterated forcing and non-existance of a model $N$ such that $\langle G_n : n \in \omega \rangle \in N$ and $\text{o}(N) = \text{o}(M)$.

Existence of Natural Numbers as an Axiom

What does a hyperreal version of the Cantor Set look like?

Sets definable by $\Sigma_2$ parameters

Von Neumann integers definition

Regularity Enforces Trivial $\in$-Isomorphisms

If $\subseteq$ is defined set-theoretically, it doesn't exist

Show the cardinality of the infinite union of sets is less than the cardinality of the Cartesian product of those sets.

Is it possible to base the slow-growing hierarchy on the ordinal defined as “the height of the minimal model of ZFC (assuming it exists)”?

How can axiomatic set theory handle real-life objects?

Is there a way to prove the Banach-Tarski theorem from just the Partition Principle?

Absent choice, if $A$ and $B$ have a bijection, must every surjective function from $A$ to $B$ have a right inverse?

How do set theorists view this issue?

Are there countably many numbers than can be described?

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