User Andreas Blass

15 votes

Second-order ordinal definability

answered Mar 24 at 20:46

7 votes

Accepted

Subset of the reals with zero inner measure and "full" outer measure in $\mathsf{ZF}+\mathsf{DC}$

answered Feb 29 at 16:50

11 votes

What would you do with a new model of linear logic?

answered Feb 23 at 19:04

9 votes

Follow up question: Shelah's "Can you take Solovay's inaccessible away?"

answered Jan 10 at 0:34

7 votes

Accepted

"Compactness length" of Baire space

answered Nov 1, 2023 at 2:11

4 votes

CH and the existence of a Borel partition of small cardinality

answered Oct 18, 2023 at 3:02

11 votes

Accepted

Maximal intersecting families on $\omega$ that are not ultrafilters

answered Oct 12, 2023 at 14:26

6 votes

Cut a homotopy in two via a "frontier"

answered Oct 10, 2023 at 18:05

7 votes

Accepted

Are sequences going to +infty along a ultrafilter on $\omega$ essentialy increasing?

answered Oct 5, 2023 at 16:06

2 votes

Existence of Brownian motion using Kolmogorov's extension theorem

answered Oct 1, 2023 at 1:16

7 votes

Accepted

Impredicativity, definition, recursion and conservatism

answered Sep 20, 2023 at 22:59

16 votes

Ultraproducts of Banach spaces versus model theoretic ultraproduct

answered May 2, 2023 at 19:14

11 votes

Does every consistent extension of ZF have a model in the minimal transitive model of ZFC?

answered Jan 2, 2023 at 0:13

6 votes

Accepted

Property ${\bf B}$ for families of large sets with small intersection

answered Nov 19, 2022 at 22:35

7 votes

Accepted

Minimum number of dense sets to make a filter an ultrafilter

answered Nov 6, 2022 at 14:57

5 votes

Accepted

Decomposition of an ultrafilter on the fibers of a map

answered Sep 4, 2022 at 22:55

2 votes

Accepted

Natural transformations between coterminal functors with differing domains

answered Jul 16, 2022 at 15:02

4 votes

Accepted

Steiner-like systems on $\omega$

answered Jul 8, 2022 at 21:05

10 votes

Existence of a homogeneous cyclic order for arbitrary infinite cardinals

answered Jul 4, 2022 at 2:14

0 votes

Existence of m infinite subsets in an arbitrary group such that all products of one element from each (in order) are distinct

answered Jun 18, 2022 at 21:38

2 votes

A question on regular sets

answered Jun 9, 2022 at 17:47

8 votes

Accepted

Are countable models constructible?

answered Feb 24, 2022 at 1:22

3 votes

When are the zero sets of two continuous functions in the Stone-Čech compactification included in one another?

answered Jan 16, 2022 at 21:47

8 votes

Accepted

Can finite sets be non-c.e. depending on how they are presented?

answered Nov 6, 2021 at 20:45

1 vote

Equivalence relations not associated with a group

answered Sep 19, 2021 at 12:18

12 votes

Accepted

Applications of ZFA-Set Theory

answered Jul 23, 2021 at 20:04

11 votes

Accepted

Images of complemented subobjects in toposes

answered Jun 22, 2021 at 23:17

5 votes

Sunflowers in $\omega$ consisting of infinite sets

answered Jun 6, 2021 at 19:01

3 votes

"Coloring" the greatest common divisor relation

answered May 24, 2021 at 14:53

2 votes

Are finite subsets of bi-immune sets random?

answered Apr 22, 2021 at 22:51

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785 Answers

Second-order ordinal definability

Subset of the reals with zero inner measure and "full" outer measure in $\mathsf{ZF}+\mathsf{DC}$

What would you do with a new model of linear logic?

Follow up question: Shelah's "Can you take Solovay's inaccessible away?"

"Compactness length" of Baire space

CH and the existence of a Borel partition of small cardinality

Maximal intersecting families on $\omega$ that are not ultrafilters

Cut a homotopy in two via a "frontier"

Are sequences going to +infty along a ultrafilter on $\omega$ essentialy increasing?

Existence of Brownian motion using Kolmogorov's extension theorem

Impredicativity, definition, recursion and conservatism

Ultraproducts of Banach spaces versus model theoretic ultraproduct

Does every consistent extension of ZF have a model in the minimal transitive model of ZFC?

Property ${\bf B}$ for families of large sets with small intersection

Minimum number of dense sets to make a filter an ultrafilter

Decomposition of an ultrafilter on the fibers of a map

Natural transformations between coterminal functors with differing domains

Steiner-like systems on $\omega$

Existence of a homogeneous cyclic order for arbitrary infinite cardinals

Existence of m infinite subsets in an arbitrary group such that all products of one element from each (in order) are distinct

A question on regular sets

Are countable models constructible?

When are the zero sets of two continuous functions in the Stone-Čech compactification included in one another?

Can finite sets be non-c.e. depending on how they are presented?

Equivalence relations not associated with a group

Applications of ZFA-Set Theory

Images of complemented subobjects in toposes

Sunflowers in $\omega$ consisting of infinite sets

"Coloring" the greatest common divisor relation

Are finite subsets of bi-immune sets random?