Question

Simplest set that requires Replacement but cannot be achieved using Power-Set

score 147 · Answer 1 · 2026-04-12 23:14:07

147

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Simplest set that requires Replacement but cannot be achieved using Power-Set

Published on 12 Apr 2026 - 23:14

score 138 · Answer 2 · 2026-04-11 00:15:45

138

Views

A question on cardinal arithmetic

Published on 11 Apr 2026 - 0:15

score 85 · Answer 3 · 2026-04-15 04:50:14

85

Views

Proving any bounded family of ordinals has a supremum

Published on 15 Apr 2026 - 4:50

score 340 · Answer 4 · 2026-04-11 21:35:25

340

Views

What system was Grothendieck working in when he introduced universes?

Published on 11 Apr 2026 - 21:35

score 145 · Answer 5 · 2026-04-12 14:32:50

145

Views

Is Von Neumann's function application operation defined for all functions and all arguments?

Published on 12 Apr 2026 - 14:32

score 329 · Answer 6 · 2026-04-13 03:11:02

329

Views

Products of ultrafilters and products of measures

Published on 13 Apr 2026 - 3:11

score 82 · Answer 7 · 2026-04-10 22:25:26

82

Views

Order Isomorphisms of $\aleph_2$

Published on 10 Apr 2026 - 22:25

score 210 · Answer 8 · 2026-04-17 09:22:32

210

Views

If $M[G]\cap M[H]=M$, must $G\times H$ be generic?

Published on 17 Apr 2026 - 9:22

score 210 · Answer 9 · 2026-04-14 08:25:17

210

Views

Regarding Extenders

Published on 14 Apr 2026 - 8:25

score 49 · Answer 10 · 2026-04-16 01:18:57

Assuming $V=L$ show that any set of integers $x\in L_{\alpha+1}$ satisfies $x\in L_{\alpha}$ where $\alpha$ is countable.

score 138 · Answer 11 · 2026-04-16 02:34:35

If $V=L$ and $\alpha<\aleph_1$, find a countable $\beta >\alpha$ s.t. when $x\in L_{\beta+1}$, $x\in L_{\beta}$

score 231 · Answer 12 · 2026-04-16 10:24:59

231

Views

Epsilon numbers: how to show $\varepsilon_{\omega_\alpha}=\omega_\alpha$ for $\alpha>0$?

Published on 16 Apr 2026 - 10:24

score 123 · Answer 13 · 2026-04-09 01:57:30

123

Views

Showing that $\kappa$ is weakly compact in ultrapower.

Published on 09 Apr 2026 - 1:57

score 77 · Answer 14 · 2026-04-10 13:06:41

77

Views

Verifying a proof (under AC) that any (possibly non-finite) graph $G$ has a $\kappa$-coloring ($\kappa$ a cardinal) if $\chi(G)\leq \kappa\leq |V(G)|$

Published on 10 Apr 2026 - 13:06

score 99 · Answer 15 · 2026-04-13 14:35:09

99

Views

Probability , Martin Axiom, and the "weak" Frankl Conjecture

Published on 13 Apr 2026 - 14:35

List Question

Simplest set that requires Replacement but cannot be achieved using Power-Set

A question on cardinal arithmetic

Proving any bounded family of ordinals has a supremum

What system was Grothendieck working in when he introduced universes?

Is Von Neumann's function application operation defined for all functions and all arguments?

Products of ultrafilters and products of measures

Order Isomorphisms of $\aleph_2$

If $M[G]\cap M[H]=M$, must $G\times H$ be generic?

Regarding Extenders

Assuming $V=L$ show that any set of integers $x\in L_{\alpha+1}$ satisfies $x\in L_{\alpha}$ where $\alpha$ is countable.

If $V=L$ and $\alpha<\aleph_1$, find a countable $\beta >\alpha$ s.t. when $x\in L_{\beta+1}$, $x\in L_{\beta}$

Epsilon numbers: how to show $\varepsilon_{\omega_\alpha}=\omega_\alpha$ for $\alpha>0$?

Showing that $\kappa$ is weakly compact in ultrapower.

Verifying a proof (under AC) that any (possibly non-finite) graph $G$ has a $\kappa$-coloring ($\kappa$ a cardinal) if $\chi(G)\leq \kappa\leq |V(G)|$

Probability , Martin Axiom, and the "weak" Frankl Conjecture

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