User Reid Barton

65 votes

Accepted

Analogue to covering space for higher homotopy groups?

answered Oct 17, 2009 at 23:45

58 votes

Accepted

What is (co)homology, and how does a beginner gain intuition about it?

answered Oct 15, 2009 at 20:46

56 votes

Why is it so cool to square numbers (in terms of finding the standard deviation)?

answered Oct 18, 2009 at 22:17

48 votes

Accepted

Can a topos ever be an abelian category?

answered Dec 31, 2009 at 17:19

47 votes

Most interesting mathematics mistake?

answered Oct 17, 2009 at 16:09

43 votes

Are there two non-homotopy equivalent spaces with equal homotopy groups?

answered Nov 1, 2009 at 15:48

42 votes

why haven't certain well-researched classes of mathematical object been framed by category theory?

answered Apr 23, 2010 at 18:04

37 votes

Example of a good Zero Knowledge Proof

answered Apr 26, 2010 at 18:38

33 votes

Accepted

Two functors from Grp to Grp?

answered Nov 5, 2009 at 17:45

33 votes

Accepted

Is there a "universal group object"? (answered: yes!)

answered Oct 20, 2009 at 4:35

31 votes

Is every finite group a group of "symmetries"?

answered Oct 18, 2009 at 4:38

30 votes

How do you keep your research notes organized?

answered Oct 22, 2009 at 3:13

29 votes

Accepted

How does one find the "loneliest person on the planet"?

answered Oct 17, 2009 at 23:24

29 votes

What is the definition of "canonical"?

answered Mar 28, 2010 at 18:36

28 votes

Accepted

Computing the structure of the group completion of an abelian monoid, how hard can it be?

answered Feb 3, 2010 at 15:01

27 votes

Why does non-abelian group cohomology exist?

answered Oct 25, 2009 at 0:13

26 votes

Accepted

Presheaves as limits of representable functors?

answered Oct 28, 2009 at 23:30

26 votes

What's a reasonable category that is not locally small?

answered Oct 29, 2009 at 17:31

26 votes

What's a groupoid? What's a good example of a groupoid?

answered Oct 19, 2009 at 4:00

26 votes

Accepted

Counter-example to the existence of left Bousfield localization of combinatorial model category

answered Mar 13, 2019 at 22:00

24 votes

Algorithm for finding the volume of a convex polytope

answered Oct 18, 2009 at 3:01

24 votes

Accepted

Can we disallow finite choice?

answered Nov 8, 2009 at 20:59

24 votes

Why are spectral sequences so ubiquitous?

answered Dec 7, 2009 at 19:08

24 votes

Accepted

Homotopy pullbacks and homotopy pushouts

answered Dec 12, 2009 at 16:49

23 votes

Why do Groups and Abelian Groups feel so different?

answered Dec 18, 2009 at 18:53

23 votes

Accepted

Functorial Whitehead Tower?

answered Nov 12, 2009 at 22:54

22 votes

Describe a topic in one sentence.

answered Nov 3, 2009 at 6:15

21 votes

Why do I find Category Theory mostly just a way to make simple things difficult?

answered Oct 24, 2009 at 16:19

21 votes

Accepted

Mathematical solution for a two-player single-suit trick taking game?

answered Feb 17, 2010 at 1:29

20 votes

Intuition behind counterexample of Euler's sum of powers conjecture

answered Mar 11, 2019 at 16:42

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202 Answers

Analogue to covering space for higher homotopy groups?

What is (co)homology, and how does a beginner gain intuition about it?

Why is it so cool to square numbers (in terms of finding the standard deviation)?

Can a topos ever be an abelian category?

Most interesting mathematics mistake?

Are there two non-homotopy equivalent spaces with equal homotopy groups?

why haven't certain well-researched classes of mathematical object been framed by category theory?

Example of a good Zero Knowledge Proof

Two functors from Grp to Grp?

Is there a "universal group object"? (answered: yes!)

Is every finite group a group of "symmetries"?

How do you keep your research notes organized?

How does one find the "loneliest person on the planet"?

What is the definition of "canonical"?

Computing the structure of the group completion of an abelian monoid, how hard can it be?

Why does non-abelian group cohomology exist?

Presheaves as limits of representable functors?

What's a reasonable category that is not locally small?

What's a groupoid? What's a good example of a groupoid?

Counter-example to the existence of left Bousfield localization of combinatorial model category

Algorithm for finding the volume of a convex polytope

Can we disallow finite choice?

Why are spectral sequences so ubiquitous?

Homotopy pullbacks and homotopy pushouts

Why do Groups and Abelian Groups feel so different?

Functorial Whitehead Tower?

Describe a topic in one sentence.

Why do I find Category Theory mostly just a way to make simple things difficult?

Mathematical solution for a two-player single-suit trick taking game?

Intuition behind counterexample of Euler's sum of powers conjecture