Question

Is $ X \to \mathrm{CH}^i (X) $ covariant or contravariant?

score 173 · Answer 1 · 2026-03-21 12:24:01

173

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Is $ X \to \mathrm{CH}^i (X) $ covariant or contravariant?

Published on 21 Mar 2026 - 12:24

score 195 · Answer 2 · 2026-03-17 11:38:41

195

Views

Question about notation for Čech cohomology and direct image of sheaves in Hartshorne

Published on 17 Mar 2026 - 11:38

score 277 · Answer 3 · 2026-03-17 11:49:33

277

Views

Does sheafification preserve surjectivity?

Published on 17 Mar 2026 - 11:49

score 183 · Answer 4 · 2026-03-17 13:38:28

183

Views

Image of a morphism of chain complexes of sheaves via direct/inverse image functor

Published on 17 Mar 2026 - 13:38

score 81 · Answer 5 · 2026-03-17 03:31:04

81

Views

Tensor of a $k[X]$ module with the structure sheaf of an affine variety is a sheaf

Published on 17 Mar 2026 - 3:31

score 696 · Answer 6 · 2026-03-17 19:03:47

696

Views

Sheafy definition for the tangent space at a point on a manifold?

Published on 17 Mar 2026 - 19:03

score 342 · Answer 7 · 2026-03-18 04:03:44

342

Views

Whats the relationship between a presheaf and its sheafification?

Published on 18 Mar 2026 - 4:03

score 83 · Answer 8 · 2026-03-17 09:05:05

83

Views

First isomorphism theorem of sheaves -- do you need to sheafify if the map is surjective on basis sets?

Published on 17 Mar 2026 - 9:05

score 183 · Answer 9 · 2026-03-17 06:48:42

183

Views

An irreducible topological space $X$ admits a constant sheaf iff it is indiscrete.

Published on 17 Mar 2026 - 6:48

score 390 · Answer 10 · 2026-03-18 01:52:33

390

Views

Why does a globally generated invertible sheaf admit a global section not vanishing on any irreducible component?

Published on 18 Mar 2026 - 1:52

score 276 · Answer 11 · 2026-03-19 22:01:23

276

Views

Viewing a closed point as a scheme

Published on 19 Mar 2026 - 22:01

score 311 · Answer 12 · 2026-03-24 23:51:35

Proof of $(D(f),\mathcal O_{\operatorname {Spec}A}|_{D(f)})\cong (\operatorname{Spec}A_f,\mathcal O_{\operatorname {Spec}A_f}) $(Vakil 4.3.B)

score 88 · Answer 13 · 2026-03-24 23:44:30

88

Views

Intersection in a Sheaf of Rings

Published on 24 Mar 2026 - 23:44

score 1k · Answer 14 · 2026-03-24 23:43:14

1k

Views

When is the structure sheaf not coherent over itself?

Published on 24 Mar 2026 - 23:43

score 154 · Answer 15 · 2026-03-20 15:11:24

154

Views

Geometric interpretation of Lawvere-Tierney topology

Published on 20 Mar 2026 - 15:11

List Question

Is $ X \to \mathrm{CH}^i (X) $ covariant or contravariant?

Question about notation for Čech cohomology and direct image of sheaves in Hartshorne

Does sheafification preserve surjectivity?

Image of a morphism of chain complexes of sheaves via direct/inverse image functor

Tensor of a $k[X]$ module with the structure sheaf of an affine variety is a sheaf

Sheafy definition for the tangent space at a point on a manifold?

Whats the relationship between a presheaf and its sheafification?

First isomorphism theorem of sheaves -- do you need to sheafify if the map is surjective on basis sets?

An irreducible topological space $X$ admits a constant sheaf iff it is indiscrete.

Why does a globally generated invertible sheaf admit a global section not vanishing on any irreducible component?

Viewing a closed point as a scheme

Proof of $(D(f),\mathcal O_{\operatorname {Spec}A}|_{D(f)})\cong (\operatorname{Spec}A_f,\mathcal O_{\operatorname {Spec}A_f}) $(Vakil 4.3.B)

Intersection in a Sheaf of Rings

When is the structure sheaf not coherent over itself?

Geometric interpretation of Lawvere-Tierney topology

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