Module

ActualFiniteInertiaContinuity.lean

Nyll.EtaleFundamentalGroups.Inertia.ActualFiniteInertiaContinuity
4 declarations indexed from sourceView source ↗

Local constancy of actual finite inertia restriction

The coefficient automorphism underlying the SAME intrinsic finite inertia restriction factors through the locally constant finite Galois restriction. Injectivity of the intrinsic subgroup inclusion then proves local constancy without installing any replacement topology on the original inertia group.

Declarations

EtaleFundamentalGroups.Inertia.actualFiniteInertiaRestriction_coefficient

The constructor for actual intrinsic restriction has the prescribed coefficient automorphism.

Source context 3 commands

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

namespace EtaleFundamentalGroups.Inertia
universe u v w
variable (A : Type u) (K : Type v) (L : Type w)
  [CommRing A] [Field K] [Field L]
  [Algebra A K] [IsFractionRing A K]
  [Algebra K L] [Algebra A L] [IsScalarTower A K L] [IsGalois K L]
theorem actualFiniteInertiaRestriction_coefficient
    (Q : Ideal (SchemeTheory.normalizationCommAlgCat A L).carrier)
    (E : FiniteGaloisIntermediateField K L)
    (σ : (actualNormalizationInertiaGroup A K L Q).carrier) :
    ((actualFiniteInertiaRestriction A K L Q E).hom'.toFun σ).val =
      (actualFiniteInertiaCoefficientMap A K L Q E).hom'.toFun σ
EtaleFundamentalGroups.Inertia.actualFiniteInertiaCoefficientMap_isLocallyConstant

The existing coefficient restriction is locally constant on original inertia by restriction of the ambient coefficient map to its subgroup.

Source context 3 commands

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

namespace EtaleFundamentalGroups.Inertia
universe u v w
variable (A : Type u) (K : Type v) (L : Type w)
  [CommRing A] [Field K] [Field L]
  [Algebra A K] [IsFractionRing A K]
  [Algebra K L] [Algebra A L] [IsScalarTower A K L] [IsGalois K L]
theorem actualFiniteInertiaCoefficientMap_isLocallyConstant
    (Q : Ideal (SchemeTheory.normalizationCommAlgCat A L).carrier)
    (E : FiniteGaloisIntermediateField K L) :
    IsLocallyConstant (actualFiniteInertiaCoefficientMap A K L Q E).hom'.toFun
EtaleFundamentalGroups.Inertia.actualFiniteInertiaRestriction_isLocallyConstant

Restricting actual original inertia to its intrinsic finite normalization inertia is locally constant for the original subgroup topology.

Source context 3 commands

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

namespace EtaleFundamentalGroups.Inertia
universe u v w
variable (A : Type u) (K : Type v) (L : Type w)
  [CommRing A] [Field K] [Field L]
  [Algebra A K] [IsFractionRing A K]
  [Algebra K L] [Algebra A L] [IsScalarTower A K L] [IsGalois K L]
theorem actualFiniteInertiaRestriction_isLocallyConstant
    (Q : Ideal (SchemeTheory.normalizationCommAlgCat A L).carrier)
    (E : FiniteGaloisIntermediateField K L) :
    IsLocallyConstant (actualFiniteInertiaRestriction A K L Q E).hom'.toFun
EtaleFundamentalGroups.Inertia.actualFiniteInertiaRestriction_continuous

The actual restriction is continuous into the discrete intrinsic finite group; more generally, it is continuous for any topology on that target.

Source context 3 commands

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

namespace EtaleFundamentalGroups.Inertia
universe u v w
variable (A : Type u) (K : Type v) (L : Type w)
  [CommRing A] [Field K] [Field L]
  [Algebra A K] [IsFractionRing A K]
  [Algebra K L] [Algebra A L] [IsScalarTower A K L] [IsGalois K L]
theorem actualFiniteInertiaRestriction_continuous
    (Q : Ideal (SchemeTheory.normalizationCommAlgCat A L).carrier)
    (E : FiniteGaloisIntermediateField K L)
    [TopologicalSpace (commAlgIdealInertiaGroup A (finiteAbsoluteNormalizationAlgebra A K L E)
      (finiteAbsoluteNormalizationPrime A K L Q E)).carrier] :
    Continuous (actualFiniteInertiaRestriction A K L Q E).hom'.toFun