Tom Leinster's user avatar
Tom Leinster's user avatar
Tom Leinster's user avatar
Tom Leinster
  • Member for 14 years, 5 months
  • Last seen this week
130 votes
Accepted

What properties make $[0,1]$ a good candidate for defining fundamental groups?

93 votes
Accepted

When is $A$ isomorphic to $A^3$?

81 votes

When are two proofs of the same theorem really different proofs

80 votes

Best online mathematics videos?

66 votes

Theorems for nothing (and the proofs for free)

60 votes

Cures for mathematician's block (as in writer's block)

54 votes

Taking lecture notes in lectures

51 votes

How do I check if a functor has a (left/right) adjoint?

51 votes

What is a metric space?

45 votes

Is the ultraproduct concept fundamentally category-theoretic?

44 votes

What are the benefits of viewing a sheaf from the "espace étalé" perspective?

37 votes

Google question: In a country in which people only want boys

36 votes
Accepted

Can epi/mono for natural transformations be checked pointwise?

36 votes
Accepted

Expressing the Lebesgue integral using categories + the difficulty of describing estimates in category theory

35 votes
Accepted

What is the name of the following categorical property?

35 votes

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

34 votes
Accepted

Good lattice theory books?

32 votes

Combinatorial results without known combinatorial proofs

31 votes

"Philosophical" meaning of the Yoneda Lemma

31 votes

Is a functor which has a left adjoint which is also its right adjoint an equivalence ?

31 votes
Accepted

Coend computation

27 votes

What's a magical theorem in logic?

27 votes

Can the opposite of an elementary topos be an elementary topos?

26 votes
Accepted

Geometric interpretations of the exponential of entropy

25 votes
Accepted

Citation of a paper with a proof you would like to improve

25 votes
Accepted

Continuous function from $[0,1]$ to $[0,1]$

24 votes
Accepted

What properties "should" spectrum of noncommutative ring have?

23 votes
Accepted

Terminology in category theory

23 votes

Are there categories whose internal hom is somewhat 'exotic'?

22 votes
Accepted

In what sense are fields an algebraic theory?

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