User Brendan McKay

43 votes

3 answers

2k views

History of the four-colour problem

asked Jan 12, 2012 at 11:38

38 votes

3 answers

4k views

finding the parity of a permutation in little space

asked Aug 11, 2011 at 8:50

31 votes

4 answers

2k views

Probability of zero in a random matrix

asked Jun 3, 2012 at 10:52

26 votes

1 answer

1k views

probability of zero subset sum

asked Jan 21, 2013 at 12:59

25 votes

3 answers

1k views

Changing the signs of the coefficients of a polynomial to make all the roots real

asked Dec 19, 2016 at 7:03

23 votes

1 answer

1k views

Jumping in the integers

asked Sep 4, 2011 at 4:47

22 votes

2 answers

2k views

Largest graphs of girth at least 6

asked Jun 16, 2012 at 4:16

21 votes

1 answer

1k views

A strange sum over bipartite graphs

asked Mar 5, 2012 at 7:00

18 votes

4 answers

2k views

Complexity of equitable partitions

asked May 13, 2012 at 23:34

17 votes

0 answers

512 views

Maximum automorphism group for a 3-connected cubic graph

asked Jul 17, 2013 at 1:29

16 votes

1 answer

2k views

Overlapping Gershgorin disks

asked Aug 13, 2011 at 13:38

14 votes

1 answer

426 views

A Collatz-like question about permutations

asked Aug 5, 2015 at 1:17

12 votes

5 answers

569 views

Intersecting 4-sets

asked Nov 6, 2012 at 2:23

11 votes

0 answers

310 views

How many n/2-cycles can a cubic graph have

asked Oct 3, 2013 at 13:44

10 votes

1 answer

585 views

Maximal subgroups of a certain finite 2-group

asked Sep 2, 2012 at 8:15

10 votes

1 answer

411 views

Network flows with capacities on pairs of edges

asked May 24, 2012 at 14:54

9 votes

2 answers

354 views

Finding local patterns in a circular list

asked Feb 21, 2012 at 14:02

9 votes

2 answers

799 views

Need to bound a trigonometric sum

asked Aug 20, 2011 at 13:13

9 votes

1 answer

326 views

Factoring a multiset into a product of two multisets

asked Feb 7, 2016 at 1:22

8 votes

0 answers

164 views

Hamiltonian paths in the prime sum graph

asked Jul 9, 2023 at 5:41

8 votes

3 answers

693 views

partly obscured Rubik's cube

asked Oct 10, 2012 at 3:12

8 votes

1 answer

732 views

6-regular bipartite graphs with no 8-cycles

asked Jul 29, 2012 at 10:55

8 votes

2 answers

1k views

Spanning trees of plane graphs containing an edge of every face

asked Nov 17, 2012 at 9:31

7 votes

0 answers

186 views

How quickly can we test if a graph is distance-regular?

asked May 1, 2013 at 7:48

7 votes

1 answer

146 views

Covering a set with images of a transversal

asked Jan 12, 2015 at 9:07

7 votes

1 answer

224 views

A polytope with a bound on the sum of any $k$ variables

asked Dec 12, 2014 at 7:00

7 votes

1 answer

202 views

What polytope is this? Bounded sums with choice of coefficients

asked Oct 11, 2015 at 4:53

6 votes

2 answers

436 views

Measurable maximal independent set in infinite graph of bounded degree

asked Feb 19, 2018 at 2:12

6 votes

2 answers

254 views

Eigenvalues of polynomials of two matrices

asked Aug 1, 2023 at 7:24

6 votes

0 answers

154 views

Distribution of iid hypergeometric random variables conditioned on the sum

asked Mar 25, 2021 at 9:49

Stack Exchange Network

56 Questions

History of the four-colour problem

finding the parity of a permutation in little space

Probability of zero in a random matrix

probability of zero subset sum

Changing the signs of the coefficients of a polynomial to make all the roots real

Jumping in the integers

Largest graphs of girth at least 6

A strange sum over bipartite graphs

Complexity of equitable partitions

Maximum automorphism group for a 3-connected cubic graph

Overlapping Gershgorin disks

A Collatz-like question about permutations

Intersecting 4-sets

How many n/2-cycles can a cubic graph have

Maximal subgroups of a certain finite 2-group

Network flows with capacities on pairs of edges

Finding local patterns in a circular list

Need to bound a trigonometric sum

Factoring a multiset into a product of two multisets

Hamiltonian paths in the prime sum graph

partly obscured Rubik's cube

6-regular bipartite graphs with no 8-cycles

Spanning trees of plane graphs containing an edge of every face

How quickly can we test if a graph is distance-regular?

Covering a set with images of a transversal

A polytope with a bound on the sum of any $k$ variables

What polytope is this? Bounded sums with choice of coefficients

Measurable maximal independent set in infinite graph of bounded degree

Eigenvalues of polynomials of two matrices

Distribution of iid hypergeometric random variables conditioned on the sum