User James E Hanson - MathOverflow

129 votes

Accepted

Czelakowski's claimed proof of the Twin Prime Conjecture

answered Oct 28, 2022 at 22:54

114 votes

Which high-degree derivatives play an essential role?

answered Jun 30, 2019 at 17:52

38 votes

Accepted

What is the consistency strength of Russell & Whitehead's ‘Principia Mathematica’?

answered Jul 21, 2025 at 22:31

36 votes

How would set theory research be affected by using ETCS instead of ZFC?

answered Dec 22, 2024 at 18:01

33 votes

Accepted

Would Hofstadter's critique of the theory of types apply to modern type theories as well?

answered Dec 27, 2025 at 22:35

32 votes

Lists as a foundation of mathematics

answered Oct 17, 2023 at 22:26

27 votes

How is it possible for PA+¬Con(PA) to be consistent?

answered Oct 5, 2023 at 5:39

27 votes

What is the most "concrete-feeling" equivalent formulation of the Continuum Hypothesis that you can think of?

answered Nov 25, 2023 at 18:39

26 votes

Type vs. Set Theory: Expressive Ability

answered Jul 29, 2024 at 6:26

25 votes

Is Bauer–Hanson’s result “there is a topos where the Dedekind reals are countable” novel?

answered Aug 23, 2023 at 16:52

23 votes

Accepted

Is the category $\mathbf{Top}^{\mathrm{op}}$ a Malcev category?

answered Mar 26 at 19:51

23 votes

Accepted

Do the constructible lines and circles (not merely their intersections) cover the plane?

answered Jul 22, 2025 at 23:19

22 votes

Accepted

Can you make products of sets associative?

answered Aug 19, 2025 at 0:16

21 votes

Accepted

Pedagogically intuitive reformulation of Zorn's Lemma for functional analysis

answered Nov 16, 2024 at 4:45

20 votes

Accepted

Category-theoretic characterization of $L$

answered Aug 7, 2024 at 20:34

19 votes

Accepted

Automorphisms over models of L?

answered Jun 22, 2025 at 23:08

18 votes

Accepted

Closed formula for the factorial over reals

answered Dec 16, 2024 at 21:32

18 votes

What would be some major consequences of the inconsistency of ZFC?

answered Jan 2, 2025 at 19:54

17 votes

Do the surreal numbers enjoy the transfer principle in ZFC?

answered Nov 25, 2024 at 3:57

16 votes

History of invariant types in model theory

answered Apr 4, 2025 at 13:34

16 votes

Why is it so hard to give examples of differentially closed fields?

answered Mar 29, 2025 at 1:15

16 votes

Why is it so difficult to define constructive cardinality?

answered Apr 24, 2025 at 17:23

16 votes

About Grothendieck UB axiom

answered Aug 2, 2025 at 20:50

16 votes

If every definable class admits a group structure, must global choice hold?

answered Jul 25, 2024 at 21:49

16 votes

Accepted

Could Kronecker accept a proof of Goodstein's theorem?

answered Mar 11, 2020 at 1:31

15 votes

Definability of Gödel's pairing function on ordinals

answered Feb 18, 2021 at 5:46

15 votes

How might mathematics have been different?

answered Jul 10, 2025 at 15:58

15 votes

Can passing to a larger Grothendieck universe ever lead to category-theoretic complications?

answered yesterday

14 votes

Can ultraproducts avoid all "factor structures"?

answered Jul 6, 2023 at 4:12

13 votes

Kuratowski's definition of ordered pairs

answered Jun 12, 2025 at 3:08

Stack Exchange Network

148 Answers

Czelakowski's claimed proof of the Twin Prime Conjecture

Which high-degree derivatives play an essential role?

What is the consistency strength of Russell & Whitehead's ‘Principia Mathematica’?

How would set theory research be affected by using ETCS instead of ZFC?

Would Hofstadter's critique of the theory of types apply to modern type theories as well?

Lists as a foundation of mathematics

How is it possible for PA+¬Con(PA) to be consistent?

What is the most "concrete-feeling" equivalent formulation of the Continuum Hypothesis that you can think of?

Type vs. Set Theory: Expressive Ability

Is Bauer–Hanson’s result “there is a topos where the Dedekind reals are countable” novel?

Is the category $\mathbf{Top}^{\mathrm{op}}$ a Malcev category?

Do the constructible lines and circles (not merely their intersections) cover the plane?

Can you make products of sets associative?

Pedagogically intuitive reformulation of Zorn's Lemma for functional analysis

Category-theoretic characterization of $L$

Automorphisms over models of L?

Closed formula for the factorial over reals

What would be some major consequences of the inconsistency of ZFC?

Do the surreal numbers enjoy the transfer principle in ZFC?

History of invariant types in model theory

Why is it so hard to give examples of differentially closed fields?

Why is it so difficult to define constructive cardinality?

About Grothendieck UB axiom

If every definable class admits a group structure, must global choice hold?

Could Kronecker accept a proof of Goodstein's theorem?

Definability of Gödel's pairing function on ordinals

How might mathematics have been different?

Can passing to a larger Grothendieck universe ever lead to category-theoretic complications?

Can ultraproducts avoid all "factor structures"?

Kuratowski's definition of ordered pairs