Module

QuasicoherentCoprod.lean

Nyll.SchemeTheory.Modules.QuasicoherentCoprod
4 declarations indexed from sourceView source ↗

Quasicoherence of actual binary coproducts

On each affine chart the tilde adjunction carries the coproduct of the two section modules to the actual sheaf coproduct. Restriction preserves this coproduct, so the affine criterion gives global quasicoherence.

Imports6
  • Nyll.SchemeTheory.Modules.QuasicoherentLocal
  • Mathlib.AlgebraicGeometry.Modules.Tilde
  • Mathlib.AlgebraicGeometry.Modules.Sheaf
  • Mathlib.CategoryTheory.Adjunction.Limits
  • Mathlib.CategoryTheory.Limits.Preserves.Shapes.BinaryProducts
  • Mathlib.CategoryTheory.Limits.Shapes.BinaryProducts.BinaryProducts
Imported by2

Declarations

AlgebraicGeometry.Scheme.Modules.tildeSectionsIso
Source context 4 commands

Surrounding namespaces, section variables, and local commands at this declaration.

noncomputable section
universe u
open CategoryTheory Limits
namespace AlgebraicGeometry.Scheme.Modules
def tildeSectionsIso {R : CommRingCat.{u}}
    (M : (Spec R).Modules) [M.IsQuasicoherent] :
    (tilde.functor R).obj ((moduleSpecΓFunctor (R := R)).obj M) ≅ M
AlgebraicGeometry.Scheme.Modules.isQuasicoherent_coprod_toSpec

Actual binary coproducts of quasicoherent modules are quasicoherent on an affine scheme.

Source context 4 commands

Surrounding namespaces, section variables, and local commands at this declaration.

noncomputable section
universe u
open CategoryTheory Limits
namespace AlgebraicGeometry.Scheme.Modules
theorem isQuasicoherent_coprod_toSpec {R : CommRingCat.{u}}
    (M N : (Spec R).Modules) [M.IsQuasicoherent] [N.IsQuasicoherent] :
    (M ⨿ N).IsQuasicoherent
AlgebraicGeometry.Scheme.Modules.isQuasicoherent_coprod

The actual binary coproduct of quasicoherent scheme modules is quasicoherent.

Source context 4 commands

Surrounding namespaces, section variables, and local commands at this declaration.

noncomputable section
universe u
open CategoryTheory Limits
namespace AlgebraicGeometry.Scheme.Modules
theorem isQuasicoherent_coprod {X : Scheme.{u}}
    (M N : X.Modules) [M.IsQuasicoherent] [N.IsQuasicoherent] :
    (M ⨿ N).IsQuasicoherent
SheafOfModules.isQuasicoherent_coprod_native

The actual native binary coproduct of quasicoherent sheaves on a scheme is quasicoherent.

Source context 4 commands

Surrounding namespaces, section variables, and local commands at this declaration.

noncomputable section
universe u
open CategoryTheory Limits
namespace SheafOfModules
theorem isQuasicoherent_coprod_native {X : AlgebraicGeometry.Scheme.{u}}
    (M N : SheafOfModules.{u} X.ringCatSheaf) [M.IsQuasicoherent] [N.IsQuasicoherent] :
    (M ⨿ N).IsQuasicoherent