User Dominic van der Zypen

9 votes

4 answers

546 views

Graph homomorphisms and line graph

asked Oct 1, 2015 at 9:11

9 votes

3 answers

792 views

Majority coloring for directed graphs

asked Mar 7, 2016 at 15:27

9 votes

2 answers

484 views

Graph $G$ with $\omega(G) = 2$ but $\chi(G) \geq \aleph_0$

asked May 20, 2015 at 9:34

9 votes

2 answers

2k views

"Gray code" of all permutations

asked Aug 29, 2017 at 12:34

9 votes

3 answers

405 views

Does the lattice of all topologies embed into the lattice of $T_1$-topologies?

asked Mar 13, 2018 at 9:41

9 votes

1 answer

488 views

Does "$X \not\to (\omega)^\omega_2$ for every infinite $X$" imply ${\sf AC}$?

asked Mar 21, 2022 at 10:28

9 votes

1 answer

352 views

Are the Boolean algebras ${\cal P}(\omega)/(\text{fin})$ and ${\cal P}(\omega)/(\text{thin})$ isomorphic?

asked Dec 21, 2023 at 15:33

9 votes

1 answer

382 views

Example of a connected graph $G$ with $G \cong G \times G$

asked Aug 4, 2022 at 7:15

9 votes

3 answers

472 views

Countable connected space where removing $1$ point destroys connectedness

asked Dec 25, 2018 at 8:35

9 votes

2 answers

436 views

Lower density of numbers not summable by consecutive integers

asked Oct 14, 2018 at 13:35

9 votes

0 answers

313 views

Uncountable group with no proper subgroup of maximal cardinal

asked Oct 30, 2019 at 16:39

8 votes

3 answers

555 views

Arranging all permutations on $\{1,\ldots,n\}$ such that there are no common points

asked May 29, 2019 at 11:29

8 votes

1 answer

550 views

Expected value of biggest distance of adjacent points uniformly picked in $[0,1]$

asked Jul 3, 2019 at 7:39

8 votes

2 answers

659 views

Exponential objects in the category of measurable spaces

asked Jul 13, 2019 at 19:44

8 votes

1 answer

260 views

Set of homeomorphic fixed points that is dense, but not equal to whole space

asked Sep 3, 2018 at 12:56

8 votes

0 answers

346 views

Model for "$\kappa$ limit cardinal iff $2^\kappa$ limit cardinal"

asked Jan 23, 2019 at 15:46

8 votes

4 answers

686 views

Are there $2^{\aleph_0}$ pairwise non-isomorphic Boolean algebra structures on $\omega$?

asked Feb 23, 2019 at 16:09

8 votes

1 answer

474 views

Scheduling "parent talks" at school

asked Jan 8, 2023 at 19:53

8 votes

1 answer

239 views

Non-Ramsey functions $c:[\omega]^\omega\to\{0,1\}$ and the Axiom of Choice

asked Jul 18, 2023 at 16:08

8 votes

2 answers

689 views

Induced subgraphs of any given smaller chromatic number

asked Jul 30, 2021 at 8:25

8 votes

3 answers

821 views

Sunflowers in maximal almost disjoint families

asked Jun 7, 2021 at 9:35

8 votes

2 answers

162 views

Neighborhood fingerprint of a graph

asked Mar 22, 2018 at 8:15

8 votes

2 answers

205 views

Spaces without maximal homogeneous subspaces

asked May 3, 2018 at 10:35

8 votes

1 answer

365 views

Model ${\sf ZF}$ that "spreads" members of ${\cal P}(X)$

asked Oct 30, 2017 at 13:43

8 votes

1 answer

181 views

Unbeatable clique covers

asked Dec 13, 2016 at 6:57

8 votes

2 answers

409 views

Space $X$ such that $X^\lambda\cong X$ for some $\lambda$

asked Jun 11, 2015 at 6:41

8 votes

3 answers

498 views

Binary relations as the topological closure of the diagonal

asked Sep 2, 2014 at 12:08

8 votes

3 answers

561 views

"All retracts are closed" as separation axiom

asked Dec 18, 2014 at 8:35

8 votes

2 answers

930 views

Co-Hausdorffification

asked Jan 30, 2015 at 8:12

8 votes

1 answer

692 views

Edge chromatic number of hypergraphs

asked Jan 11, 2016 at 16:33

Stack Exchange Network

1,151 Questions

Graph homomorphisms and line graph

Majority coloring for directed graphs

Graph $G$ with $\omega(G) = 2$ but $\chi(G) \geq \aleph_0$

"Gray code" of all permutations

Does the lattice of all topologies embed into the lattice of $T_1$-topologies?

Does "$X \not\to (\omega)^\omega_2$ for every infinite $X$" imply ${\sf AC}$?

Are the Boolean algebras ${\cal P}(\omega)/(\text{fin})$ and ${\cal P}(\omega)/(\text{thin})$ isomorphic?

Example of a connected graph $G$ with $G \cong G \times G$

Countable connected space where removing $1$ point destroys connectedness

Lower density of numbers not summable by consecutive integers

Uncountable group with no proper subgroup of maximal cardinal

Arranging all permutations on $\{1,\ldots,n\}$ such that there are no common points

Expected value of biggest distance of adjacent points uniformly picked in $[0,1]$

Exponential objects in the category of measurable spaces

Set of homeomorphic fixed points that is dense, but not equal to whole space

Model for "$\kappa$ limit cardinal iff $2^\kappa$ limit cardinal"

Are there $2^{\aleph_0}$ pairwise non-isomorphic Boolean algebra structures on $\omega$?

Scheduling "parent talks" at school

Non-Ramsey functions $c:[\omega]^\omega\to\{0,1\}$ and the Axiom of Choice

Induced subgraphs of any given smaller chromatic number

Sunflowers in maximal almost disjoint families

Neighborhood fingerprint of a graph

Spaces without maximal homogeneous subspaces

Model ${\sf ZF}$ that "spreads" members of ${\cal P}(X)$

Unbeatable clique covers

Space $X$ such that $X^\lambda\cong X$ for some $\lambda$

Binary relations as the topological closure of the diagonal

"All retracts are closed" as separation axiom

Co-Hausdorffification

Edge chromatic number of hypergraphs