Andrew Stacey's user avatar
Andrew Stacey's user avatar
Andrew Stacey's user avatar
Andrew Stacey
  • Member for 14 years, 6 months
  • Last seen more than a week ago
79 votes
10 answers
10k views

What are the uses of the homotopy groups of spheres?

76 votes
34 answers
7k views

Dimension leaps

75 votes
8 answers
17k views

What is an intuitive view of adjoints? (version 1: category theory)

71 votes
2 answers
6k views

Barrelled, bornological, ultrabornological, semi-reflexive, ... how are these used?

58 votes
22 answers
14k views

How to respond to "I was never much good at maths at school." [closed]

51 votes
25 answers
11k views

Theorems for nothing (and the proofs for free) [closed]

50 votes
6 answers
10k views

What does actually being a CW-complex provide in algebraic topology?

49 votes
1 answer
5k views

Is it best to run or walk in the rain? [closed]

44 votes
7 answers
9k views

What's an example of a space that needs the Hahn-Banach Theorem?

42 votes
8 answers
5k views

What is a metric space?

42 votes
7 answers
14k views

What is an intuitive view of adjoints? (version 2: functional analysis)

41 votes
15 answers
12k views

What's so great about blackboards? [closed]

37 votes
1 answer
2k views

Wanted, dead or alive: Have you seen this curve? (circular variant of cardioid)

34 votes
5 answers
13k views

Linearity of the inner product using the parallelogram law

31 votes
3 answers
5k views

Is "compact implies sequentially compact" consistent with ZF?

28 votes
2 answers
4k views

Terminology in category theory

26 votes
2 answers
2k views

When is a locally convex topological vector space normal or paracompact?

17 votes
5 answers
822 views

How can one characterise compactness-by-experiment?

15 votes
3 answers
8k views

What is an isomorphism of Banach spaces?

15 votes
4 answers
2k views

Can one do without Riesz Representation?

15 votes
2 answers
2k views

What is a projective space?

14 votes
3 answers
1k views

What is a monoidal metric space?

13 votes
4 answers
2k views

Is the category of Banach spaces with contractions an algebraic theory?

13 votes
6 answers
3k views

When does local invertibility imply invertibility?

10 votes
1 answer
619 views

What's the nearest algebraic theory to inner product spaces?

10 votes
3 answers
3k views

Reference request: gluing manifolds along pieces of boundary

9 votes
4 answers
9k views

Applications of Euler-Cauchy ODEs

9 votes
1 answer
861 views

Is there a notion of a "perfectly regular" topological space?

8 votes
3 answers
586 views

Compact Hausdorff and C^*-algebra "objects" in a category.

7 votes
4 answers
5k views

Beamer hints and tips [closed]