Module

InjectiveModuleLocalization.lean

Nyll.EtaleFundamentalGroups.Purity.InjectiveModuleLocalization
2 declarations indexed from sourceView source ↗

Localization of an injective module

Over a Noetherian ring the localization map of an injective module is surjective. Stabilization of the kernels of powers of a denominator makes an appropriate division map well-defined on a principal ideal; injectivity extends that map to the ring. For a principal localization the kernel is exactly the principal ideal-power torsion submodule.

Imports6
  • Mathlib.Algebra.Module.Injective
  • Mathlib.Algebra.Module.LocalizedModule.Basic
  • Mathlib.Algebra.Module.Torsion.PrimaryComponent
  • Mathlib.LinearAlgebra.Isomorphisms
  • Mathlib.RingTheory.Ideal.Operations
  • Mathlib.RingTheory.Noetherian.Defs
Imported by3

Declarations

EtaleFundamentalGroups.Purity.localizedModule_mkLinearMap_surjective_of_injective

Localization of an injective module over a Noetherian ring is a quotient of the original module.

Source context 5 commands

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

noncomputable section
namespace EtaleFundamentalGroups.Purity
universe u
variable {R : Type u} [CommRing R]
variable (E : Type u) [AddCommGroup E] [Module R E]
theorem localizedModule_mkLinearMap_surjective_of_injective
    [IsNoetherianRing R] [Module.Injective R E] (S : Submonoid R) :
    Function.Surjective (LocalizedModule.mkLinearMap S E)
EtaleFundamentalGroups.Purity.ker_localizedModule_mkLinearMap_powers

The kernel of principal localization is principal ideal-power torsion.

Source context 5 commands

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

noncomputable section
namespace EtaleFundamentalGroups.Purity
universe u
variable {R : Type u} [CommRing R]
variable (E : Type u) [AddCommGroup E] [Module R E]
theorem ker_localizedModule_mkLinearMap_powers (x : R) :
    LinearMap.ker (LocalizedModule.mkLinearMap (Submonoid.powers x) E) =
      Ideal.primaryComponent E (Ideal.span {x})