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user332
  • Member for 13 years, 3 months
79 votes
8 answers
13k views

What is the motivation for a vertex algebra?

51 votes
9 answers
8k views

Nice proofs of the Poincaré–Birkhoff–Witt theorem

28 votes
1 answer
2k views

How were moduli spaces defined before functors?

26 votes
4 answers
2k views

What is an example of a presheaf P where P^+ is not a sheaf, only a separated presheaf?

24 votes
4 answers
4k views

Motivation/interpretation for Quillen's Q-construction?

18 votes
4 answers
3k views

Techniques for computing cup products in singular cohomology

12 votes
4 answers
1k views

For which hypersurfaces in projective space does the complement admit an algebraic group structure?

8 votes
2 answers
407 views

Doing explicit computations with coordinate rings

8 votes
2 answers
1k views

Notes for Bott's 1963 lectures on Morse theory

7 votes
2 answers
885 views

Example of a measure-preserving system with dense orbits that is not ergodic

5 votes
4 answers
3k views

Interesting examples of flasque sheaves?