Module

NormalizationPrime.lean

Nyll.EtaleFundamentalGroups.StrictHenselian.NormalizationPrime
2 declarations indexed from sourceView source ↗

Strict Henselianity of an actual normalization prime localization

The integral closure in an algebraic separably closed extension has that extension as its fraction field, by the native algebraic integral-closure owner. Its literal prime localization is normal and has the same fraction field through the existing prescribed localization map. The established separably closed fraction-field theorem therefore proves strict Henselianity. No finite extension, Noetherianity, or separately chosen local model is used.

Declarations

EtaleFundamentalGroups.StrictHenselian.primeLocalization_strictHenselian
Source context 3 commands

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

noncomputable section
namespace EtaleFundamentalGroups.StrictHenselian
universe u v w
theorem primeLocalization_strictHenselian
    (B : Type u) (L : Type v) [CommRing B] [IsDomain B] [IsIntegrallyClosed B]
    [Field L] [Algebra B L] [IsFractionRing B L] [IsSepClosed L]
    (Q : Ideal B) [Q.IsPrime] :
    HenselianLocalRing (Localization.AtPrime Q) ∧
      IsSepClosed (IsLocalRing.ResidueField (Localization.AtPrime Q))
EtaleFundamentalGroups.StrictHenselian.integralClosure_localizationAtPrime_strictHenselian

The literal localization of the integral closure at any prime is strictly Henselian when the ambient algebraic extension is separably closed. The base need only be a domain with the displayed fraction field; its normality and localness are not needed for this supplier.

Source context 3 commands

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

noncomputable section
namespace EtaleFundamentalGroups.StrictHenselian
universe u v w
theorem integralClosure_localizationAtPrime_strictHenselian
    (A : Type u) (K : Type v) (L : Type w)
    [CommRing A] [IsDomain A] [Field K] [Field L]
    [Algebra A K] [IsFractionRing A K] [Algebra K L] [Algebra A L]
    [IsScalarTower A K L] [Algebra.IsAlgebraic K L] [IsSepClosed L]
    (Q : Ideal (integralClosure A L)) [Q.IsPrime] :
    HenselianLocalRing (Localization.AtPrime Q) ∧
      IsSepClosed (IsLocalRing.ResidueField (Localization.AtPrime Q))