User Piotr Achinger

5 votes

Frobenius splitting and derived Cartier isomorphism

answered Sep 29, 2011 at 1:13

5 votes

Blow-ups of $\mathbb{P}^{n-3}$ and $(\mathbb{P}^1)^{n-3}$

answered Dec 22, 2014 at 2:35

5 votes

Accepted

Relative flasqueness?

answered Feb 20, 2014 at 22:51

5 votes

Existence of local sections

answered Apr 6, 2014 at 17:36

5 votes

flatness criterion on normal bases

answered Dec 23, 2012 at 0:25

5 votes

Accepted

Theta group representation

answered Feb 8, 2013 at 2:37

5 votes

Accepted

Local rings $R \subsetneq S$ with $R$ regular and $S$ Cohen-Macaulay, non-regular

answered Apr 20, 2021 at 5:21

5 votes

Is it true that $\operatorname{2-colim}_U \textsf{QCoh}(U) = \textsf{Vect}(K_X)$, as $U$ shrinks to the generic point?

answered Jun 5, 2022 at 8:44

5 votes

Accepted

"Non-algebraic" Berkovich spaces

answered Mar 1, 2023 at 16:23

4 votes

Accepted

Proper smooth pushforward of vector bundle is a vector bundle?

answered Nov 11 at 12:43

4 votes

Accepted

Surjectivity of specialization map

answered Nov 19 at 8:04

4 votes

Accepted

Subsheaves of a locally free sheaf on $P^{d}$

answered Oct 17, 2022 at 15:19

4 votes

Accepted

globally $F$-regular type variety and vanishing theorem

answered Jun 3 at 8:42

4 votes

Adic generic fiber of a small formal scheme in the sense of Faltings

answered Oct 9, 2023 at 11:24

4 votes

Accepted

Tangent Space of the Hodge bundle on the moduli space of curves

answered Apr 20, 2021 at 9:19

4 votes

Accepted

Homotopy Ehresmann and deformation invariance of $l$-adic Chern classes

answered Aug 23, 2020 at 20:10

4 votes

Relating the toric rank of a semistable curve and the first Betti number of its reduction graph

answered Nov 30, 2012 at 23:50

4 votes

What is the algebraic geometry version of the spheres?

answered Dec 7, 2012 at 3:00

4 votes

Accepted

On the infinitesimal lifting property of non-singular affine schemes

answered Nov 10, 2014 at 0:16

4 votes

Examples for D-affine varieties?

answered Nov 3, 2011 at 7:48

4 votes

Accepted

Smooth algebras always lift

answered May 17, 2018 at 18:04

4 votes

Is the map on étale fundamental groups of a quasi-projective variety, upon base change between algebraically closed fields, an isomorphism?

answered Dec 21, 2016 at 11:40

4 votes

Singularities of the moduli stack of polarized hyperkahler varieties

answered Apr 27, 2015 at 18:37

4 votes

Accepted

Ehresmann's theorem for singular varieties

answered Jul 5, 2017 at 13:59

4 votes

Accepted

Lifting of Frobenius on torsors over abelian varieties

answered Mar 12, 2016 at 13:38

4 votes

Accepted

Lifting of Frobenius on semi-abelian varieties

answered Mar 12, 2016 at 14:18

4 votes

Hodge standard conjecture in positive characteristic

answered May 3, 2020 at 10:11

4 votes

Accepted

"Holomorphic line bundle" + "algebraic after finite cover" implies "algebraic"?

answered Jun 9, 2020 at 14:04

4 votes

Fundamental group of an open subscheme of a normal scheme

answered Nov 19, 2018 at 17:02

4 votes

When can you resolve rational maps to proper stacks by blowing up?

answered Jun 27, 2018 at 19:46

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187 Answers

Frobenius splitting and derived Cartier isomorphism

Blow-ups of $\mathbb{P}^{n-3}$ and $(\mathbb{P}^1)^{n-3}$

Relative flasqueness?

Existence of local sections

flatness criterion on normal bases

Theta group representation

Local rings $R \subsetneq S$ with $R$ regular and $S$ Cohen-Macaulay, non-regular

Is it true that $\operatorname{2-colim}_U \textsf{QCoh}(U) = \textsf{Vect}(K_X)$, as $U$ shrinks to the generic point?

"Non-algebraic" Berkovich spaces

Proper smooth pushforward of vector bundle is a vector bundle?

Surjectivity of specialization map

Subsheaves of a locally free sheaf on $P^{d}$

globally $F$-regular type variety and vanishing theorem

Adic generic fiber of a small formal scheme in the sense of Faltings

Tangent Space of the Hodge bundle on the moduli space of curves

Homotopy Ehresmann and deformation invariance of $l$-adic Chern classes

Relating the toric rank of a semistable curve and the first Betti number of its reduction graph

What is the algebraic geometry version of the spheres?

On the infinitesimal lifting property of non-singular affine schemes

Examples for D-affine varieties?

Smooth algebras always lift

Is the map on étale fundamental groups of a quasi-projective variety, upon base change between algebraically closed fields, an isomorphism?

Singularities of the moduli stack of polarized hyperkahler varieties

Ehresmann's theorem for singular varieties

Lifting of Frobenius on torsors over abelian varieties

Lifting of Frobenius on semi-abelian varieties

Hodge standard conjecture in positive characteristic

"Holomorphic line bundle" + "algebraic after finite cover" implies "algebraic"?

Fundamental group of an open subscheme of a normal scheme

When can you resolve rational maps to proper stacks by blowing up?