User Tony Huynh

96 votes

16 answers

34k views

Most 'unintuitive' application of the Axiom of Choice?

asked Apr 10, 2010 at 1:21

64 votes

16 answers

13k views

How helpful is non-standard analysis?

asked Feb 24, 2010 at 22:26

56 votes

21 answers

14k views

Linear algebra proofs in combinatorics?

asked Mar 3, 2010 at 20:39

49 votes

15 answers

11k views

Strengthening the induction hypothesis

asked Jul 13, 2010 at 13:01

48 votes

5 answers

8k views

Algebraic proof of 4-colour theorem?

asked Mar 24, 2010 at 21:59

44 votes

5 answers

24k views

Does pi contain 1000 consecutive zeroes (in base 10)?

asked May 5, 2010 at 4:41

30 votes

8 answers

3k views

Cryptomorphisms

asked Feb 18, 2010 at 17:25

20 votes

2 answers

2k views

Simple curves on non-orientable surfaces.

asked Nov 1, 2010 at 16:23

19 votes

3 answers

1k views

Drawing planar graphs with integer edge lengths

asked Feb 2, 2011 at 15:57

18 votes

2 answers

4k views

Turning pants inside-out (or backwards) while tied together

asked Apr 18, 2010 at 23:39

18 votes

3 answers

8k views

Number of invertible {0,1} real matrices?

asked Mar 18, 2010 at 18:49

17 votes

1 answer

1k views

Is there a Sudoku matroid?

asked May 4, 2013 at 2:14

13 votes

2 answers

374 views

Set family $\mathcal{F}$ such that for all $A,B,C \in \mathcal{F}$ both $A \cap B \not \subseteq C$ and $C \not \subseteq A \cup B $

asked Aug 10, 2017 at 11:08

13 votes

2 answers

1k views

Ultrafilters vs Well-orderings

asked Apr 11, 2010 at 19:28

12 votes

5 answers

6k views

Subset of the plane that intersects every line exactly twice

asked Apr 15, 2010 at 16:08

11 votes

3 answers

2k views

Easier induction proofs by changing the parameter

asked Jan 11, 2011 at 15:00

11 votes

1 answer

2k views

What is the size of a largest antichain in this poset?

asked Sep 29, 2011 at 3:30

10 votes

1 answer

312 views

Is this drawing of $K_{4,4}$ knotted?

asked Oct 22, 2021 at 1:36

10 votes

2 answers

595 views

Transfinite algorithms

asked Apr 8, 2020 at 8:04

8 votes

1 answer

238 views

Functions over monoids which factor in two different ways

asked Jul 27, 2021 at 9:18

8 votes

0 answers

152 views

Disjoint Rooted Paths with Specified Patterns

asked Sep 20, 2010 at 12:34

5 votes

2 answers

1k views

Degree sequences of multigraphs with bounded multiplicity

asked Jul 27, 2010 at 13:09

3 votes

1 answer

321 views

Removing intersections of curves in surfaces

asked Jul 31, 2010 at 1:27

3 votes

2 answers

331 views

Does this set family have a name?

asked Nov 16, 2010 at 10:05

3 votes

3 answers

2k views

Homology with Coefficients

asked Mar 18, 2010 at 21:59

3 votes

3 answers

6k views

Homology of Surfaces with Holes

asked Mar 20, 2010 at 16:23

1 vote

4 answers

754 views

What is the quantity 2(handles)+crosscaps called?

asked May 5, 2011 at 20:46

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27 Questions

Most 'unintuitive' application of the Axiom of Choice?

How helpful is non-standard analysis?

Linear algebra proofs in combinatorics?

Strengthening the induction hypothesis

Algebraic proof of 4-colour theorem?

Does pi contain 1000 consecutive zeroes (in base 10)?

Cryptomorphisms

Simple curves on non-orientable surfaces.

Drawing planar graphs with integer edge lengths

Turning pants inside-out (or backwards) while tied together

Number of invertible {0,1} real matrices?

Is there a Sudoku matroid?

Set family $\mathcal{F}$ such that for all $A,B,C \in \mathcal{F}$ both $A \cap B \not \subseteq C$ and $C \not \subseteq A \cup B $

Ultrafilters vs Well-orderings

Subset of the plane that intersects every line exactly twice

Easier induction proofs by changing the parameter

What is the size of a largest antichain in this poset?

Is this drawing of $K_{4,4}$ knotted?

Transfinite algorithms

Functions over monoids which factor in two different ways

Disjoint Rooted Paths with Specified Patterns

Degree sequences of multigraphs with bounded multiplicity

Removing intersections of curves in surfaces

Does this set family have a name?

Homology with Coefficients

Homology of Surfaces with Holes

What is the quantity 2(handles)+crosscaps called?