User Asaf Karagila

257 votes

6 answers

27k views

In (relatively) simple words: What is an inverse limit?

asked May 11, 2011 at 18:11

106 votes

3 answers

14k views

Why are vector spaces not isomorphic to their duals?

asked Aug 19, 2011 at 19:04

51 votes

3 answers

8k views

How far are the $p$-adic numbers from being algebraically closed?

asked Jan 7, 2011 at 22:49

35 votes

3 answers

3k views

What does the topology on $\operatorname{Spec}(R)$ tells us about $R$?

asked Feb 10, 2013 at 22:22

31 votes

1 answer

4k views

Metrizable compactifications

asked Sep 8, 2011 at 12:33

30 votes

2 answers

2k views

Why algebraic closures?

asked Jul 15, 2012 at 13:48

25 votes

1 answer

1k views

On the large cardinals foundations of categories

asked Apr 28, 2013 at 10:00

24 votes

7 answers

9k views

Subset of a finite set is finite

asked Nov 18, 2012 at 1:39

22 votes

2 answers

3k views

What do linearly ordered abelian groups look like?

asked May 21, 2013 at 3:45

17 votes

1 answer

662 views

Is this a characterization of well-orders?

asked Jul 7, 2013 at 1:00

16 votes

2 answers

516 views

Is there a direct proof that a compact unit ball implies automatic continuity?

asked Dec 15, 2015 at 5:54

16 votes

1 answer

912 views

Forcing Classes Into Sets

asked Feb 14, 2011 at 23:28

15 votes

1 answer

2k views

Completely metrizable implies $G_\delta$

asked Sep 9, 2011 at 8:19

14 votes

1 answer

415 views

What is the degree of a real closure of an ordered field?

asked May 13, 2015 at 5:18

13 votes

1 answer

531 views

Extending open maps to Stone-Čech compactifications

asked Sep 21, 2011 at 14:04

13 votes

1 answer

1k views

Surreal numbers without the axiom of infinity

asked Nov 1, 2011 at 22:06

12 votes

1 answer

391 views

Definable order types without infinity axiom.

asked May 8, 2012 at 15:30

12 votes

2 answers

2k views

No uncountable ordinals without the axiom of choice?

asked May 11, 2011 at 14:37

12 votes

2 answers

955 views

When does $V=L$ becomes inconsistent?

asked May 18, 2011 at 21:10

12 votes

5 answers

445 views

Summable enumerations of $\Bbb Q$

asked Sep 23, 2014 at 4:51

11 votes

2 answers

818 views

Real-measurable cardinals that are not measurable ones

asked Sep 27, 2010 at 23:13

10 votes

1 answer

374 views

$A^\#$ and inner models

asked Jul 27, 2011 at 16:25

10 votes

1 answer

685 views

Consistency of $\operatorname{cf}(\omega_1)=\operatorname{cf}(\omega_2)=\omega$

asked Jul 31, 2011 at 14:45

10 votes

2 answers

820 views

Fodor's lemma on singular cardinals

asked Aug 10, 2011 at 18:14

9 votes

1 answer

653 views

$\Sigma_{\alpha+1}^0(X)$ universal set based on the Baire space

asked Jul 5, 2011 at 13:15

9 votes

1 answer

458 views

Forcing cardinality of a set

asked Jan 23, 2011 at 19:03

9 votes

3 answers

450 views

Does this logic have the downward Skolem-Löwenheim theorem?

asked Jun 4, 2013 at 1:48

9 votes

3 answers

279 views

Computing how many distinct digital products are below $10^n$

asked Apr 23, 2019 at 9:15

8 votes

3 answers

662 views

Can $(\Bbb N,\leq)$ have an $\aleph_0$-categorical theory (in a larger language)?

asked Jun 23, 2014 at 17:16

8 votes

1 answer

426 views

Universal sets in metric spaces

asked May 3, 2011 at 9:09

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59 Questions

In (relatively) simple words: What is an inverse limit?

Why are vector spaces not isomorphic to their duals?

How far are the $p$-adic numbers from being algebraically closed?

What does the topology on $\operatorname{Spec}(R)$ tells us about $R$?

Metrizable compactifications

Why algebraic closures?

On the large cardinals foundations of categories

Subset of a finite set is finite

What do linearly ordered abelian groups look like?

Is this a characterization of well-orders?

Is there a direct proof that a compact unit ball implies automatic continuity?

Forcing Classes Into Sets

Completely metrizable implies $G_\delta$

What is the degree of a real closure of an ordered field?

Extending open maps to Stone-Čech compactifications

Surreal numbers without the axiom of infinity

Definable order types without infinity axiom.

No uncountable ordinals without the axiom of choice?

When does $V=L$ becomes inconsistent?

Summable enumerations of $\Bbb Q$

Real-measurable cardinals that are not measurable ones

$A^\#$ and inner models

Consistency of $\operatorname{cf}(\omega_1)=\operatorname{cf}(\omega_2)=\omega$

Fodor's lemma on singular cardinals

$\Sigma_{\alpha+1}^0(X)$ universal set based on the Baire space

Forcing cardinality of a set

Does this logic have the downward Skolem-Löwenheim theorem?

Computing how many distinct digital products are below $10^n$

Can $(\Bbb N,\leq)$ have an $\aleph_0$-categorical theory (in a larger language)?

Universal sets in metric spaces