User Simon Rose

56 votes

3 answers

8k views

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

asked May 7, 2012 at 21:01

16 votes

1 answer

869 views

Can one determine the dimension of a manifold given its 1-skeleton?

asked Jan 6, 2019 at 19:31

16 votes

3 answers

2k views

How do modular forms of half-integral weight relate to the (quasi-modular) Eisenstein series?

asked Sep 8, 2010 at 18:28

3 votes

2 answers

1k views

Is there a lower bound for the computational complexity of the traveling salesman problem?

asked Nov 12, 2017 at 14:26

16 votes

0 answers

1k views

How many sporadic simple groups are there, really?

asked Dec 10, 2013 at 18:02

32 votes

3 answers

3k views

Is there a nice explanation for this curious fact about cyclic subgroups?

asked Jun 3, 2016 at 9:43

21 votes

1 answer

320 views

How many ways can I factor a matrix (over $\mathbb{Z}$)?

asked Mar 29, 2016 at 14:01

1 vote

1 answer

494 views

Is there a nice choice-free argument to count the number of sublattices?

asked Feb 1, 2016 at 10:52

3 votes

2 answers

422 views

Is there a nice generating function proof of the following identity?

asked Oct 28, 2015 at 12:40

10 votes

1 answer

290 views

What can we say about tropical maps $\mathbb{P}^1 \to A$ for an Abelian variety $A$?

asked Oct 5, 2015 at 11:11

4 votes

0 answers

107 views

Is there a nice way to invert this expression?

asked Sep 8, 2015 at 8:30

51 votes

3 answers

7k views

What is the purpose of the flat/fppf/fpqc topologies?

asked Jan 29, 2015 at 10:33

2 votes

1 answer

201 views

What is the value of this hyperelliptic Hodge-type integral?

asked Jan 14, 2015 at 15:06

14 votes

0 answers

520 views

Am I missing something about this notion of Mirror Symmetry for abelian varieties?

asked Dec 1, 2014 at 12:48

8 votes

0 answers

392 views

Mirror symmetry for polarized abelian surfaces and Shioda-Inose K3s

asked Nov 19, 2014 at 14:11

2 votes

2 answers

926 views

What is the difference between the moduli space of curves and the moduli space of orbi-curves?

asked Oct 22, 2014 at 10:50

3 votes

1 answer

306 views

Is there a nice way to write the generating function obtained by taking the quadratic coefficients of another one?

asked Jun 12, 2014 at 23:09

9 votes

1 answer

268 views

How is the propagator computed on an elliptic curve?

asked May 13, 2014 at 20:08

4 votes

2 answers

830 views

What literature is known about MacMahon's generalized sum-of-divisors function?

asked Oct 7, 2010 at 21:15

6 votes

1 answer

279 views

Does the following operation on modular forms yield something modular?

asked Nov 20, 2013 at 21:34

7 votes

2 answers

2k views

What is a good reference (preferably thorough) for the Derived Category of a scheme/orbifold/stack?

asked May 10, 2013 at 15:04

0 votes

0 answers

122 views

Obstruction theories on non-smooth spaces with smooth fibres

asked Mar 28, 2012 at 19:28

7 votes

1 answer

942 views

Trivial obstructions and virtual fundamental classes

asked Dec 19, 2011 at 22:25

8 votes

1 answer

758 views

To what extent does Poincare duality hold on moduli stacks?

asked Nov 24, 2011 at 0:03

9 votes

1 answer

700 views

How do the rings of level $N$ quasi-modular forms related to the rings of modular forms?

asked Oct 31, 2011 at 2:48

6 votes

3 answers

3k views

What is this restricted sum of multinomial coefficients?

asked Aug 24, 2011 at 22:06

13 votes

1 answer

627 views

What relations exist among (quasi-) modular forms of different levels?

asked Mar 22, 2011 at 22:39

13 votes

1 answer

2k views

Why isn't the orbifold cohomology of $pt/G$ equal to the cohomology of $BG$?

asked Mar 3, 2011 at 0:02

8 votes

3 answers

3k views

Why can we define the moment map in this way (i.e. why is this form exact)?

asked Feb 14, 2011 at 20:41

9 votes

3 answers

982 views

Is there an intrinsic way to define the group law on Abelian varieties?

asked May 19, 2010 at 18:14

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35 Questions

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

Can one determine the dimension of a manifold given its 1-skeleton?

How do modular forms of half-integral weight relate to the (quasi-modular) Eisenstein series?

Is there a lower bound for the computational complexity of the traveling salesman problem?

How many sporadic simple groups are there, really?

Is there a nice explanation for this curious fact about cyclic subgroups?

How many ways can I factor a matrix (over $\mathbb{Z}$)?

Is there a nice choice-free argument to count the number of sublattices?

Is there a nice generating function proof of the following identity?

What can we say about tropical maps $\mathbb{P}^1 \to A$ for an Abelian variety $A$?

Is there a nice way to invert this expression?

What is the purpose of the flat/fppf/fpqc topologies?

What is the value of this hyperelliptic Hodge-type integral?

Am I missing something about this notion of Mirror Symmetry for abelian varieties?

Mirror symmetry for polarized abelian surfaces and Shioda-Inose K3s

What is the difference between the moduli space of curves and the moduli space of orbi-curves?

Is there a nice way to write the generating function obtained by taking the quadratic coefficients of another one?

How is the propagator computed on an elliptic curve?

What literature is known about MacMahon's generalized sum-of-divisors function?

Does the following operation on modular forms yield something modular?

What is a good reference (preferably thorough) for the Derived Category of a scheme/orbifold/stack?

Obstruction theories on non-smooth spaces with smooth fibres

Trivial obstructions and virtual fundamental classes

To what extent does Poincare duality hold on moduli stacks?

How do the rings of level $N$ quasi-modular forms related to the rings of modular forms?

What is this restricted sum of multinomial coefficients?

What relations exist among (quasi-) modular forms of different levels?

Why isn't the orbifold cohomology of $pt/G$ equal to the cohomology of $BG$?

Why can we define the moment map in this way (i.e. why is this form exact)?

Is there an intrinsic way to define the group law on Abelian varieties?