User Piotr Achinger

10 votes

Confusion about good reduction

answered Jun 13, 2019 at 21:31

10 votes

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Can distinct morphisms between curves induce the same morphism on singular cohomology?

answered Apr 9, 2019 at 23:01

10 votes

Pushforward of invertible sheaf on $P^1$ by finite flat map

answered Apr 24, 2019 at 3:59

9 votes

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Why is, for a group scheme of finite type, "smooth" (resp. irreducible) equivalent to "geometrically reduced" (resp. geometrically irreducible)?

answered Mar 7, 2019 at 19:18

9 votes

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Does a torus action with isolated fixed points imply rational?

answered May 28, 2018 at 12:32

9 votes

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Relationship between étale and topological $K(\pi,1)$s

answered Jul 26, 2015 at 9:44

9 votes

difference between the small and big étale/flat/... site

answered Dec 24, 2016 at 10:41

9 votes

What are the general techniques for proving a variety is not toric?

answered Jan 17, 2013 at 6:49

9 votes

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Non-separatedness of moduli space of sheaves

answered Mar 1, 2014 at 9:22

9 votes

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Depth zero, high dimension

answered Nov 28, 2012 at 5:04

9 votes

On some finiteness properties for schemes

answered Nov 7, 2012 at 5:43

9 votes

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Is anything known about de Rham $K(\pi,1)$'s?

answered Jul 4, 2023 at 15:28

8 votes

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Pullback of a connection

answered Nov 3, 2020 at 13:13

8 votes

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Uniqueness of Stein factorization

answered Sep 16, 2020 at 11:43

8 votes

Projectives in the category of coherent sheaves on a projective variety

answered Oct 12, 2012 at 5:41

8 votes

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Can a non-trivial algebraic variety carry a vector bundle whose total space is affine space?

answered Jun 2, 2019 at 8:25

8 votes

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Is there an algorithm on an infinite time Turing machine to compute a dense subset of $M_g$ for large $g$?

answered Jul 2, 2020 at 18:12

7 votes

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$p$-adic Kato--Nakayama space

answered May 11, 2019 at 16:06

7 votes

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Etale homotopy type of non-unibranch scheme over $\mathbb{C}$

answered Dec 3, 2018 at 20:04

7 votes

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A weak version of high dimensional Abhyankar's conjecture

answered Jun 25, 2017 at 20:55

7 votes

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Group cohomology of fundamental group of a curve

answered May 18, 2016 at 21:57

7 votes

Relation between $h^1(\mathcal{O}_X)$, $h^0(\Omega_X)$, and first betti number for general complex manifold?

answered Oct 18, 2016 at 8:44

7 votes

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Definition of the differential of the Cone of a morphism of complexes

answered Feb 11, 2016 at 18:49

7 votes

Differential algebraic geometry vs Diffiety theory

answered Jun 20, 2018 at 19:03

7 votes

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Local to global deformation of invertible sheaves

answered May 26, 2018 at 21:09

7 votes

Evidences on Hartshorne's conjecture? References?

answered Aug 13, 2012 at 22:45

7 votes

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Commuting Matrices and the Weak Nullstellensatz

answered Oct 23, 2010 at 16:43

7 votes

When does $\operatorname{Aut}(X)=\operatorname{Bir}(X)$ hold?

answered Jan 31, 2013 at 1:19

7 votes

Help with understanding a rigid geometry proof

answered Sep 17 at 6:34

7 votes

Accepted

Finitely generated $\mathbb{Z}$-algebra embeds into unramified $p$-adic ring

answered Oct 24, 2023 at 14:52

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187 Answers

Confusion about good reduction

Can distinct morphisms between curves induce the same morphism on singular cohomology?

Pushforward of invertible sheaf on $P^1$ by finite flat map

Why is, for a group scheme of finite type, "smooth" (resp. irreducible) equivalent to "geometrically reduced" (resp. geometrically irreducible)?

Does a torus action with isolated fixed points imply rational?

Relationship between étale and topological $K(\pi,1)$s

difference between the small and big étale/flat/... site

What are the general techniques for proving a variety is not toric?

Non-separatedness of moduli space of sheaves

Depth zero, high dimension

On some finiteness properties for schemes

Is anything known about de Rham $K(\pi,1)$'s?

Pullback of a connection

Uniqueness of Stein factorization

Projectives in the category of coherent sheaves on a projective variety

Can a non-trivial algebraic variety carry a vector bundle whose total space is affine space?

Is there an algorithm on an infinite time Turing machine to compute a dense subset of $M_g$ for large $g$?

$p$-adic Kato--Nakayama space

Etale homotopy type of non-unibranch scheme over $\mathbb{C}$

A weak version of high dimensional Abhyankar's conjecture

Group cohomology of fundamental group of a curve

Relation between $h^1(\mathcal{O}_X)$, $h^0(\Omega_X)$, and first betti number for general complex manifold?

Definition of the differential of the Cone of a morphism of complexes

Differential algebraic geometry vs Diffiety theory

Local to global deformation of invertible sheaves

Evidences on Hartshorne's conjecture? References?

Commuting Matrices and the Weak Nullstellensatz

When does $\operatorname{Aut}(X)=\operatorname{Bir}(X)$ hold?

Help with understanding a rigid geometry proof

Finitely generated $\mathbb{Z}$-algebra embeds into unramified $p$-adic ring