User Chris Schommer-Pries

66 votes

1 answer

2k views

Is there an octonionic analog of the K3 surface, with implications for stable homotopy groups of spheres?

asked Sep 14, 2015 at 15:45

62 votes

7 answers

6k views

Are higher categories useful?

asked Dec 8, 2011 at 17:00

38 votes

4 answers

5k views

Invertible matrices of natural numbers are permutations... why?

asked Apr 18, 2011 at 14:16

35 votes

1 answer

1k views

Finding the octonionic analog of the K3 surface, via (almost) hyperkahler geometry?

asked Sep 17, 2015 at 14:19

34 votes

2 answers

5k views

Example Wanted: When Does Čech Cohomology Fail to be the same as Derived Functor Cohomology?

asked Mar 25, 2010 at 14:48

31 votes

3 answers

2k views

Is the counit of geometric realization a Serre fibration?

asked Jun 24, 2013 at 11:39

29 votes

4 answers

1k views

Which stable homotopy groups are represented by parallelizable manifolds?

asked Jun 25, 2020 at 17:53

29 votes

2 answers

9k views

Torsors in Algebraic Geometry?

asked Mar 25, 2010 at 18:27

27 votes

13 answers

4k views

Homological algebra for commutative monoids?

asked Oct 13, 2009 at 16:23

27 votes

3 answers

3k views

Why is this not an algebraic space?

asked Dec 15, 2009 at 21:06

27 votes

2 answers

2k views

Are the mapping class groups of manifolds finitely presentable?

asked Mar 29, 2014 at 0:33

26 votes

1 answer

1k views

Why are quasitopological spaces needed in sheaf theoretic approaches to the h-principle?

asked Mar 15, 2013 at 13:47

26 votes

2 answers

2k views

Loop Spaces as Generalized Smooth spaces or as Infinite dimensional Manifolds?

asked Jan 22, 2010 at 16:13

25 votes

4 answers

3k views

A Peculiar Model Structure on Simplicial Sets?

asked Feb 5, 2010 at 13:53

24 votes

6 answers

2k views

Simplicial model of Hopf map?

asked Oct 28, 2009 at 14:24

23 votes

5 answers

3k views

Do all 3D TQFTs come from Reshetikhin-Turaev?

asked Oct 12, 2009 at 21:23

23 votes

0 answers

700 views

Do most manifolds have symmetries? or not?

asked Jul 27, 2021 at 19:45

22 votes

4 answers

2k views

Functorial Whitehead Tower?

asked Nov 12, 2009 at 22:24

22 votes

2 answers

2k views

Lax Functors and Equivalence of Bicategories?

asked Dec 3, 2009 at 13:59

20 votes

2 answers

1k views

How many model categories have the same weak equivalences?

asked Jul 1, 2010 at 4:34

19 votes

4 answers

3k views

What are the fibrant objects in the injective model structure?

asked Dec 21, 2009 at 17:08

19 votes

1 answer

2k views

Integral cohomology ring of K(Z,3)

asked Aug 31, 2015 at 9:08

19 votes

3 answers

608 views

Characterizing Groupoids via Quotients?

asked Sep 13, 2011 at 21:28

18 votes

1 answer

2k views

A Model Category of Segal Spaces?

asked Jun 27, 2010 at 19:59

16 votes

5 answers

2k views

Elliptic Curves over F_1?

asked Dec 8, 2009 at 14:43

16 votes

1 answer

2k views

Why does the singular simplicial space geometrically realize to the original space?

asked Jun 12, 2014 at 10:30

16 votes

1 answer

1k views

Easiest example where pseudo-isotopy fails to be the same as isotopy?

asked Sep 8, 2016 at 21:24

15 votes

2 answers

1k views

Categorifying the Reals via von Neumann Algebras?

asked Oct 21, 2009 at 2:46

14 votes

0 answers

800 views

How to see the quaternionic hopf map generates the stable 3-stem?

asked Feb 19, 2013 at 22:27

14 votes

1 answer

919 views

What is known about exotic spheres up to stable diffeomorphism?

asked Feb 26, 2021 at 15:32

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74 Questions

Is there an octonionic analog of the K3 surface, with implications for stable homotopy groups of spheres?

Are higher categories useful?

Invertible matrices of natural numbers are permutations... why?

Finding the octonionic analog of the K3 surface, via (almost) hyperkahler geometry?

Example Wanted: When Does Čech Cohomology Fail to be the same as Derived Functor Cohomology?

Is the counit of geometric realization a Serre fibration?

Which stable homotopy groups are represented by parallelizable manifolds?

Torsors in Algebraic Geometry?

Homological algebra for commutative monoids?

Why is this not an algebraic space?

Are the mapping class groups of manifolds finitely presentable?

Why are quasitopological spaces needed in sheaf theoretic approaches to the h-principle?

Loop Spaces as Generalized Smooth spaces or as Infinite dimensional Manifolds?

A Peculiar Model Structure on Simplicial Sets?

Simplicial model of Hopf map?

Do all 3D TQFTs come from Reshetikhin-Turaev?

Do most manifolds have symmetries? or not?

Functorial Whitehead Tower?

Lax Functors and Equivalence of Bicategories?

How many model categories have the same weak equivalences?

What are the fibrant objects in the injective model structure?

Integral cohomology ring of K(Z,3)

Characterizing Groupoids via Quotients?

A Model Category of Segal Spaces?

Elliptic Curves over F_1?

Why does the singular simplicial space geometrically realize to the original space?

Easiest example where pseudo-isotopy fails to be the same as isotopy?

Categorifying the Reals via von Neumann Algebras?

How to see the quaternionic hopf map generates the stable 3-stem?

What is known about exotic spheres up to stable diffeomorphism?