User Piotr Achinger

20 votes

2 answers

2k views

Frobenius splitting and derived Cartier isomorphism

asked Mar 21, 2011 at 15:05

17 votes

1 answer

1k views

Existence of non-split vector bundles on smooth projective varieties

asked Mar 23, 2013 at 21:19

17 votes

1 answer

846 views

Are deformations of a scheme some kind of a "derived gerbe" under the cotangent complex?

asked Feb 3, 2014 at 6:50

16 votes

0 answers

1k views

Homology classes of subvarieties of toric varieties

asked Sep 15, 2012 at 16:58

16 votes

1 answer

1k views

$\infty$-operads and $E_\infty$-algebras

asked Mar 29, 2018 at 10:31

15 votes

0 answers

517 views

Zariski vs etale torsors over abelian varieties

asked Dec 23, 2016 at 15:33

15 votes

0 answers

2k views

Why was it so difficult to define the relative de Rham-Witt complex?

asked Dec 16, 2013 at 9:02

14 votes

1 answer

1k views

Frobenius splitting of Fano varieties

asked Sep 13, 2012 at 5:24

14 votes

0 answers

567 views

(When) is isomorphism on differentials enough to guarantee that a map is étale?

asked May 23, 2014 at 3:21

13 votes

0 answers

560 views

When does an $E_\infty$ algebra come from a commutative differential graded algebra?

asked Mar 5, 2016 at 10:48

13 votes

2 answers

2k views

Fixed Point Property in Algebraic Geometry

asked Mar 16, 2010 at 18:17

12 votes

1 answer

509 views

Can a covering space of the $p$-adic disc split over the circle?

asked May 26, 2020 at 11:37

11 votes

0 answers

375 views

Quasi-separated rigid-analytic space without a formal model?

asked Feb 10, 2021 at 17:48

10 votes

4 answers

3k views

Cohomology of line bundles

asked Aug 28, 2012 at 2:40

10 votes

2 answers

2k views

Algebraic definition of the Kuranishi map

asked Jan 14, 2013 at 23:38

9 votes

1 answer

1k views

Serre duality and Hirzebruch-Riemann-Roch in the non-projective case

asked Sep 8, 2012 at 19:39

9 votes

1 answer

346 views

Good reduction of rational surfaces

asked Jul 20, 2019 at 19:55

8 votes

3 answers

473 views

Laurent polynomials with constant term of their $(p-1)$-st power congruent to one modulo $p$

asked Feb 9, 2011 at 10:50

8 votes

1 answer

942 views

Locally constant constructible vs locally constant

asked Feb 24, 2014 at 7:36

7 votes

5 answers

868 views

Principal bundles over groups

asked Feb 14, 2011 at 13:29

7 votes

0 answers

202 views

Finite generation and finite presentation over a truncated valuation ring: is there an easier proof?

asked Sep 25 at 12:40

7 votes

1 answer

874 views

Can one prove that toric varieties are Cohen-Macaulay by finding a regular sequence?

asked Mar 15, 2014 at 18:40

7 votes

1 answer

450 views

Can we normalize a complex analytic space in a covering of an open subset?

asked Oct 2, 2014 at 6:32

6 votes

1 answer

359 views

Homotopy cosheaf?

asked Feb 21, 2018 at 12:19

6 votes

1 answer

496 views

Structure of iterated $\mathbb{P}^1$-bundles

asked Oct 22, 2010 at 14:28

6 votes

1 answer

269 views

Does there exist a relative compactification with flat boundary?

asked Mar 1, 2014 at 8:19

5 votes

1 answer

1k views

Picard groups of abelian étale covers

asked Aug 19, 2012 at 22:56

5 votes

1 answer

451 views

Is the ring $\mathbb{Z}_p [[x]]\otimes_{\mathbb{Z}_p} \overline{\mathbb{Q}}_p$ Noetherian?

asked Mar 17, 2015 at 17:24

4 votes

5 answers

2k views

What properties define open loci in families?

asked Mar 8, 2011 at 9:44

4 votes

1 answer

1k views

Formal criterion of flatness

asked Jan 30, 2013 at 0:19

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34 Questions

Frobenius splitting and derived Cartier isomorphism

Existence of non-split vector bundles on smooth projective varieties

Are deformations of a scheme some kind of a "derived gerbe" under the cotangent complex?

Homology classes of subvarieties of toric varieties

$\infty$-operads and $E_\infty$-algebras

Zariski vs etale torsors over abelian varieties

Why was it so difficult to define the relative de Rham-Witt complex?

Frobenius splitting of Fano varieties

(When) is isomorphism on differentials enough to guarantee that a map is étale?

When does an $E_\infty$ algebra come from a commutative differential graded algebra?

Fixed Point Property in Algebraic Geometry

Can a covering space of the $p$-adic disc split over the circle?

Quasi-separated rigid-analytic space without a formal model?

Cohomology of line bundles

Algebraic definition of the Kuranishi map

Serre duality and Hirzebruch-Riemann-Roch in the non-projective case

Good reduction of rational surfaces

Laurent polynomials with constant term of their $(p-1)$-st power congruent to one modulo $p$

Locally constant constructible vs locally constant

Principal bundles over groups

Finite generation and finite presentation over a truncated valuation ring: is there an easier proof?

Can one prove that toric varieties are Cohen-Macaulay by finding a regular sequence?

Can we normalize a complex analytic space in a covering of an open subset?

Homotopy cosheaf?

Structure of iterated $\mathbb{P}^1$-bundles

Does there exist a relative compactification with flat boundary?

Picard groups of abelian étale covers

Is the ring $\mathbb{Z}_p [[x]]\otimes_{\mathbb{Z}_p} \overline{\mathbb{Q}}_p$ Noetherian?

What properties define open loci in families?

Formal criterion of flatness