Module

OriginalFiniteCanonicalRootsAction.lean

Nyll.EtaleFundamentalGroups.Inertia.OriginalFiniteCanonicalRootsAction
2 declarations indexed from sourceView source ↗

Original residue actions on finite tame roots

Constructs the root map induced by an original residue automorphism and identifies it with the action of the corresponding normalization stabilizer image.

Declarations

EtaleFundamentalGroups.Inertia.originalFiniteNormalizationResidueRootsMap

The given element of the original residue target acts on the full finite tame roots through the fixed native residue roots map.

Source context 4 commands

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

noncomputable section
namespace EtaleFundamentalGroups.Inertia
open SchemeTheory
universe u v w
def originalFiniteNormalizationResidueRootsMap
    (A : Type u) (K : Type v) (F : Type w)
    [CommRing A] [IsDomain A] [IsDiscreteValuationRing A]
    [Field K] [Field F] [Algebra A K] [IsFractionRing A K]
    [Algebra K F] [Algebra A F] [IsScalarTower A K F]
    [FiniteDimensional K F] [IsGalois K F]
    (Q : Ideal (normalizationCommAlgCat A F)) [Q.IsMaximal]
    (ρ : normalizationResidueAutomorphisms A F Q) :
    GrpCat.Hom (originalFiniteNormalizationTameRootsGroup A K F Q)
      (originalFiniteNormalizationTameRootsGroup A K F Q)
EtaleFundamentalGroups.Inertia.originalFiniteNormalizationStabilizerRootsMap_eq_residue

The actual normalization D-image and the SAME original residue morphism induce identical root maps. The equality is supplied by the proved coefficient comparison, before an original inertia element is introduced.

Source context 4 commands

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

noncomputable section
namespace EtaleFundamentalGroups.Inertia
open SchemeTheory
universe u v w
theorem originalFiniteNormalizationStabilizerRootsMap_eq_residue
    (A : Type u) (K : Type v) (F : Type w)
    [CommRing A] [IsDomain A] [IsDiscreteValuationRing A]
    [Field K] [Field F] [Algebra A K] [IsFractionRing A K]
    [Algebra K F] [Algebra A F] [IsScalarTower A K F]
    [FiniteDimensional K F] [IsGalois K F]
    (Q : Ideal (normalizationCommAlgCat A F)) [Q.IsMaximal]
    (d : normalizationDecompositionGroup A K F Q) :
    let : IsDedekindDomain (normalizationCommAlgCat A F) :=
      integralClosure.isDedekindDomain A K F
    commAlgStabilizerCanonicalRootsMap A (normalizationCommAlgCat A F) Q
        (originalFiniteNormalizationPrime_ne_bot A K F Q)
        ((originalFiniteNormalizationDecompositionMorphism A K F Q).hom'.toFun d) =
      originalFiniteNormalizationResidueRootsMap A K F Q
        ((normalizationResidueMorphism A K F Q).hom'.toFun d) := by
  intro normalizationDedekind
  exact congrArg
    (commAlgCanonicalResidueRootsMap A (normalizationCommAlgCat A F) Q
      (originalFiniteNormalizationPrime_ne_bot A K F Q))
    (originalFiniteNormalizationDecompositionMorphism_residue A K F Q d).symm