Module

FiniteTypeQuotient.lean

Nyll.SchemeTheory.Modules.FiniteTypeQuotient
2 declarations indexed from sourceView source ↗

Finite type passes to actual epimorphic quotients

The original local generating covers are retained. Restriction to a slice is a left adjoint, so the actual restricted morphisms are epimorphisms; their images of the original finite generators generate the quotient.

Imports4
  • Mathlib.Algebra.Category.ModuleCat.Sheaf.Generators
  • Mathlib.Algebra.Category.ModuleCat.Sheaf.Abelian
  • Mathlib.CategoryTheory.Adjunction.Limits
  • Mathlib.CategoryTheory.Functor.EpiMono
Imported by3

Declarations

SheafOfModules.isFiniteType_of_epi

An epimorphic quotient of a finite-type sheaf of modules is finite type.

Source context 5 commands

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

noncomputable section
universe u v
open CategoryTheory Limits
namespace SheafOfModules
variable {C : Type u} [Category.{v} C] [HasBinaryProducts C]
  {J : GrothendieckTopology C} {R : Sheaf J RingCat.{u}}
  [∀ X : C, HasSheafify (J.over X) AddCommGrpCat.{u}]
  [∀ X : C, (J.over X).WEqualsLocallyBijective AddCommGrpCat.{u}]
theorem isFiniteType_of_epi {M N : SheafOfModules.{u} R}
    (f : M ⟶ N) [Epi f] [M.IsFiniteType] : N.IsFiniteType
SheafOfModules.isFiniteType_of_iso

Finite type is transported along an actual isomorphism.

Source context 5 commands

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

noncomputable section
universe u v
open CategoryTheory Limits
namespace SheafOfModules
variable {C : Type u} [Category.{v} C] [HasBinaryProducts C]
  {J : GrothendieckTopology C} {R : Sheaf J RingCat.{u}}
  [∀ X : C, HasSheafify (J.over X) AddCommGrpCat.{u}]
  [∀ X : C, (J.over X).WEqualsLocallyBijective AddCommGrpCat.{u}]
theorem isFiniteType_of_iso {M N : SheafOfModules.{u} R}
    (e : M ≅ N) [M.IsFiniteType] : N.IsFiniteType