User Joe Lamond - MathOverflow

31 votes

3 answers

3k views

Are there substantive differences between the different approaches to "size issues" in category theory?

asked Jun 24, 2024 at 12:24

24 votes

1 answer

2k views

Is Zorn's Lemma equivalent to the Axiom of Choice for individual sets?

asked Oct 2, 2025 at 15:38

21 votes

7 answers

7k views

Why do infinite-dimensional vector spaces usually have additional structure?

asked Aug 16, 2023 at 14:07

17 votes

5 answers

2k views

In what sense does the sentence $\operatorname{con}(\mathsf{PA})$ "say" that $\mathsf{PA}$ is consistent?

asked Nov 23, 2023 at 17:43

12 votes

1 answer

697 views

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

asked Apr 28 at 10:51

4 votes

0 answers

381 views

What is known about the number of elements needed to generate a given ideal in $k[X_1,\dots,X_n]$?

asked Feb 9, 2024 at 23:25

3 votes

1 answer

394 views

In a nonempty Baire space, the first player does not have a winning strategy in the Choquet Game

asked Aug 7, 2025 at 22:16

2 votes

1 answer

650 views

Is there a non-Hausdorff topological group $G$ where every point has a compact neighbourhood, but $G$ is not locally compact?

asked May 12, 2025 at 20:45

1 vote

1 answer

330 views

Origin of the pattern of prime symbols in writing short exact sequences

asked Jan 28, 2025 at 21:22

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9 Questions

Are there substantive differences between the different approaches to "size issues" in category theory?

Is Zorn's Lemma equivalent to the Axiom of Choice for individual sets?

Why do infinite-dimensional vector spaces usually have additional structure?

In what sense does the sentence $\operatorname{con}(\mathsf{PA})$ "say" that $\mathsf{PA}$ is consistent?

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

What is known about the number of elements needed to generate a given ideal in $k[X_1,\dots,X_n]$?

In a nonempty Baire space, the first player does not have a winning strategy in the Choquet Game

Is there a non-Hausdorff topological group $G$ where every point has a compact neighbourhood, but $G$ is not locally compact?

Origin of the pattern of prime symbols in writing short exact sequences