User Lisa S.

16 votes

2 answers

1k views

Grothendieck spectral sequence when one of the functors is contravariant

asked Dec 27, 2015 at 0:37

14 votes

3 answers

1k views

Are there nonisotrivial elliptic curves over $\mathbb{G}_m$?

asked Dec 12, 2014 at 3:25

14 votes

0 answers

1k views

A slick proof (?) of Zariski-Nagata purity in characteristic $p$

asked Sep 28, 2017 at 18:00

13 votes

1 answer

759 views

Is there a unique commutative group structure on $\mathbb{G}_m$?

asked Apr 20, 2015 at 1:30

13 votes

2 answers

668 views

Infinitesimal deformations of the formal group of $\mathbb{G}_m$

asked May 6, 2015 at 16:18

12 votes

1 answer

774 views

Is every proper regular relative algebraic space curve over a Dedekind domain projective?

asked May 24, 2015 at 4:11

11 votes

3 answers

1k views

Quotient of a smooth curve by a finite group and differentials

asked Dec 23, 2015 at 21:40

10 votes

1 answer

1k views

Reinterpreting Galois descent over finite fields

asked Oct 19, 2015 at 1:52

10 votes

1 answer

1k views

A proper smooth surface is projective

asked Feb 25, 2015 at 5:46

9 votes

1 answer

462 views

Elliptic curves with the same mod $p$ representation

asked May 5, 2017 at 4:02

8 votes

1 answer

676 views

$p$-adic completeness of the ring of Witt vectors

asked Jun 4, 2016 at 10:46

8 votes

1 answer

1k views

Does the ring of invariants inherit normality?

asked Mar 3, 2015 at 3:05

7 votes

0 answers

174 views

How to compactify $\mathbb{Z}_p[x, y, z]/(xyz - p)$?

asked Feb 8, 2017 at 1:48

7 votes

2 answers

766 views

$p$-torsion of an abelian variety of $p$-rank $0$

asked Nov 22, 2015 at 22:13

7 votes

1 answer

475 views

Is an elliptic curve that is isomorphic to its Frobenius conjugate defined over $\mathbb{F}_p$?

asked Oct 9, 2015 at 2:52

7 votes

1 answer

673 views

Depth under localization over a Cohen-Macaulay ring

asked Dec 27, 2017 at 16:24

7 votes

0 answers

221 views

Embedding a given affine variety as a divisor

asked Jul 24, 2018 at 6:35

6 votes

0 answers

219 views

A lisse mixed sheaf as an extension of pure lisse sheaves

asked May 10, 2020 at 17:37

6 votes

1 answer

501 views

Extensions of an abelian variety by a torus vs. extensions of their $\ell$-adic Tate modules

asked Jan 10, 2015 at 1:48

5 votes

1 answer

210 views

The generic fiber pullback for $p$-divisible groups in characteristic $p$

asked Dec 28, 2014 at 16:59

5 votes

2 answers

1k views

Is a normal proper relative curve over a DVR projective?

asked Apr 6, 2015 at 0:35

5 votes

1 answer

723 views

Is the ring of invariants Noetherian?

asked Mar 1, 2015 at 0:41

5 votes

1 answer

716 views

Lie algebra and base change

asked Oct 12, 2015 at 0:33

5 votes

1 answer

790 views

Identifying the canonical principal polarization of a Jacobian

asked Mar 14, 2016 at 1:34

5 votes

0 answers

322 views

Ultrapower of a field is purely transcendental

asked Mar 24, 2019 at 20:47

4 votes

1 answer

506 views

Is a universally closed monomorphism a closed immersion?

asked Jul 15, 2019 at 21:23

4 votes

0 answers

166 views

Can nonflat deformations of singularities always produce Cohen-Macaulay rings?

asked Jul 28, 2018 at 9:15

4 votes

1 answer

703 views

An explicit formula for Weil pairing on a complex torus

asked Feb 13, 2015 at 14:53

4 votes

2 answers

224 views

Fixed space of the square of a symmetric matrix over $\mathbb{F}_2$

asked Mar 10, 2015 at 23:51

4 votes

0 answers

333 views

Symmetric power of an etale map of curves

asked Jan 19, 2015 at 6:50

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42 Questions

Grothendieck spectral sequence when one of the functors is contravariant

Are there nonisotrivial elliptic curves over $\mathbb{G}_m$?

A slick proof (?) of Zariski-Nagata purity in characteristic $p$

Is there a unique commutative group structure on $\mathbb{G}_m$?

Infinitesimal deformations of the formal group of $\mathbb{G}_m$

Is every proper regular relative algebraic space curve over a Dedekind domain projective?

Quotient of a smooth curve by a finite group and differentials

Reinterpreting Galois descent over finite fields

A proper smooth surface is projective

Elliptic curves with the same mod $p$ representation

$p$-adic completeness of the ring of Witt vectors

Does the ring of invariants inherit normality?

How to compactify $\mathbb{Z}_p[x, y, z]/(xyz - p)$?

$p$-torsion of an abelian variety of $p$-rank $0$

Is an elliptic curve that is isomorphic to its Frobenius conjugate defined over $\mathbb{F}_p$?

Depth under localization over a Cohen-Macaulay ring

Embedding a given affine variety as a divisor

A lisse mixed sheaf as an extension of pure lisse sheaves

Extensions of an abelian variety by a torus vs. extensions of their $\ell$-adic Tate modules

The generic fiber pullback for $p$-divisible groups in characteristic $p$

Is a normal proper relative curve over a DVR projective?

Is the ring of invariants Noetherian?

Lie algebra and base change

Identifying the canonical principal polarization of a Jacobian

Ultrapower of a field is purely transcendental

Is a universally closed monomorphism a closed immersion?

Can nonflat deformations of singularities always produce Cohen-Macaulay rings?

An explicit formula for Weil pairing on a complex torus

Fixed space of the square of a symmetric matrix over $\mathbb{F}_2$

Symmetric power of an etale map of curves