some guy on the street's user avatar
some guy on the street's user avatar
some guy on the street's user avatar
some guy on the street
  • Member for 14 years, 4 months
12 votes
Accepted

Geometric meaning of torsion in homotopy groups

11 votes

How should one present curl and divergence in an undergraduate multivariable calculus class?

10 votes

Thom's Principle: rich structures are more numerous in low dimension

8 votes

A programming language that can only create algorithms with polynomial runtime?

8 votes

Clearing misconceptions: Defining "is a model of ZFC" in ZFC

8 votes
Accepted

Subset of the plane that intersects every line exactly twice

8 votes

When is a Riemannian manifold an open subset of a complete one?

5 votes

Why should I prefer bundles to (surjective) submersions?

5 votes

Side-Angle-Side Congruence and the Parallel Postulate

5 votes
Accepted

What is the precise relationship between "prodsimplicial sets" and rooted trees?

4 votes
Accepted

Conventional names for finite categories

4 votes

Tracking spectral sequence differentials

4 votes

What do people mean by "subcategory"?

4 votes

Theorems for nothing (and the proofs for free)

4 votes

Testing for Riemannian isometry

3 votes

Efficiently sampling points uniformly from the surface of an n-sphere

3 votes

What is the earliest definition given by a universal mapping property?

3 votes

Associativity with infinite nesting

2 votes
Accepted

Homology or cohomology?

2 votes

Boundary of planar region

2 votes

What is your favorite isomorphism?

2 votes

A conceptual proof that local fibrations over paracompact spaces are global fibrations?

2 votes

Do the empty set AND the entire set really need to be open?

2 votes

How to motivate the skein relations?

2 votes
Accepted

Is there a category-theoretic definition of the arithmetic Grothendieck group

2 votes

When and why do universal objects have extra properties?

2 votes

Heuristic explanation of why we lose projectives in sheaves.

1 vote

When shorter means smaller?

1 vote

Are all mathematical theorems necessarily true?

1 vote

Name for "lower/upper bounds" of arbitrary relations?