User Derek Allums

33 votes

2 answers

6k views

How should I think about very ample sheaves?

asked Feb 26, 2013 at 21:33

18 votes

2 answers

4k views

Does there exist a category in which there are no products or coproducts for reasons other than the category is too small?

asked Jan 20, 2013 at 13:43

14 votes

4 answers

875 views

Show $\mathbb{Q}[x,y]/\langle x,y \rangle$ is Not Projective as a $\mathbb{Q}[x,y]$-Module.

asked May 30, 2012 at 0:53

12 votes

2 answers

921 views

Holomorphic function on the unit disk $f$, show the set $z,w\in \mathbb{C}$ such that $f(z)=f(w)$ is not countable

asked Dec 30, 2012 at 19:17

12 votes

2 answers

444 views

Is the product of non-separated schemes non-separated?

asked Jun 19, 2013 at 16:57

10 votes

1 answer

334 views

Which definition of dimension came first?

asked Sep 30, 2012 at 15:22

9 votes

1 answer

3k views

Canonical and terminal singularities

asked Jan 27, 2014 at 1:55

8 votes

1 answer

411 views

Is $i\notin \mathbb{Q}(\zeta_p)$ for all odd primes $p$?

asked Jun 24, 2012 at 17:18

8 votes

3 answers

3k views

Elements of finite order in $SL_2(\mathbb{Z})$

asked Jun 30, 2012 at 16:29

7 votes

1 answer

401 views

A Gröbner Basis Computation Gone Bad

asked Jul 17, 2012 at 19:16

7 votes

1 answer

1k views

Is every proper nontrivial ideal in a Noetherian ring not flat?

asked Jun 1, 2012 at 19:39

7 votes

0 answers

469 views

The theorem on formal functions

asked Nov 7, 2013 at 1:14

6 votes

2 answers

128 views

Is there a fundamental reason to expect $e$ to appear in this probability question?

asked Jul 25, 2017 at 20:01

5 votes

1 answer

729 views

$j$-invariant for a singular curve

asked Oct 16, 2011 at 13:32

4 votes

1 answer

326 views

Show $A$ is "real-equivalent" to its transpose

asked Jul 24, 2012 at 18:50

4 votes

2 answers

2k views

For $K$ the splitting field of $x^8+1$ over $\mathbb{Q}$, determine $Gal(K/\mathbb{Q})$.

asked May 26, 2012 at 0:53

3 votes

1 answer

110 views

What is the "purely elementary reasoning" that the number of distinct prime factors of $n$ grows like $\frac{\log n}{\log \log n}$? [duplicate]

asked Jul 6, 2017 at 13:41

1 vote

1 answer

656 views

Detecting the type of singularity with the Jacobian

asked Oct 10, 2012 at 21:48

1 vote

0 answers

118 views

Addition law on moduli space of curves

asked Nov 17, 2012 at 0:06

1 vote

0 answers

86 views

Computing the inverse to a rational map

asked Jan 26, 2016 at 13:43

1 vote

0 answers

130 views

Degree of a ruled surface

asked Feb 18, 2016 at 18:57

1 vote

0 answers

495 views

The product of (first) chern classes

asked Mar 11, 2016 at 19:31

1 vote

1 answer

241 views

Gaps in the Genera of Space Curves

asked May 5, 2012 at 21:43

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23 Questions

How should I think about very ample sheaves?

Does there exist a category in which there are no products or coproducts for reasons other than the category is too small?

Show $\mathbb{Q}[x,y]/\langle x,y \rangle$ is Not Projective as a $\mathbb{Q}[x,y]$-Module.

Holomorphic function on the unit disk $f$, show the set $z,w\in \mathbb{C}$ such that $f(z)=f(w)$ is not countable

Is the product of non-separated schemes non-separated?

Which definition of dimension came first?

Canonical and terminal singularities

Is $i\notin \mathbb{Q}(\zeta_p)$ for all odd primes $p$?

Elements of finite order in $SL_2(\mathbb{Z})$

A Gröbner Basis Computation Gone Bad

Is every proper nontrivial ideal in a Noetherian ring not flat?

The theorem on formal functions

Is there a fundamental reason to expect $e$ to appear in this probability question?

$j$-invariant for a singular curve

Show $A$ is "real-equivalent" to its transpose

For $K$ the splitting field of $x^8+1$ over $\mathbb{Q}$, determine $Gal(K/\mathbb{Q})$.

What is the "purely elementary reasoning" that the number of distinct prime factors of $n$ grows like $\frac{\log n}{\log \log n}$? [duplicate]

Detecting the type of singularity with the Jacobian

Addition law on moduli space of curves

Computing the inverse to a rational map

Degree of a ruled surface

The product of (first) chern classes

Gaps in the Genera of Space Curves