Module

ActualTameCharacter.lean

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

The actual canonical tame character

Constructs the group homomorphism from the original inertia into the literal inverse limit of roots in the original normalization quotient. Evaluation at a degree is the stage-independent actual canonical finite coordinate.

Declarations

EtaleFundamentalGroups.Inertia.actualTameCharacter

The canonical character into the SAME literal quotient-root limit.

Source context 6 commands

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

noncomputable section
namespace EtaleFundamentalGroups.Inertia
open SchemeTheory ProCGroups.InverseSystems
universe u v w
attribute [local instance] Ideal.Quotient.field
variable (A : Type u) (K : Type v) (L : Type w)
  [CommRing A] [IsDomain A] [IsDiscreteValuationRing A]
  [Field K] [Field L] [Algebra A K] [IsFractionRing A K]
  [Algebra K L] [Algebra A L] [IsScalarTower A K L] [IsGalois K L]
  (Q : Ideal (normalizationCommAlgCat A L).carrier) [Q.IsMaximal]
def actualTameCharacter :
    (actualNormalizationInertiaGroup A K L Q).carrier →*
      (actualFiniteTameRootsSystem A K L Q).inverseLimit where
  toFun := (actualFiniteTameRootsSystem A K L Q).inverseLimitLift
    (fun n => (actualTameCoordinate A K L Q n).toFun)
    (actualTameCoordinate_compatible A K L Q)
  map_one' := by
    apply (actualFiniteTameRootsSystem A K L Q).ext
    intro n
    exact (actualTameCoordinate A K L Q n).map_one'
  map_mul' σ τ := by
    apply (actualFiniteTameRootsSystem A K L Q).ext
    intro n
    exact (actualTameCoordinate A K L Q n).map_mul' σ τ
EtaleFundamentalGroups.Inertia.actualTameCharacter_projection

Evaluation of the actual character is the proved canonical coordinate.

Source context 6 commands

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

noncomputable section
namespace EtaleFundamentalGroups.Inertia
open SchemeTheory ProCGroups.InverseSystems
universe u v w
attribute [local instance] Ideal.Quotient.field
variable (A : Type u) (K : Type v) (L : Type w)
  [CommRing A] [IsDomain A] [IsDiscreteValuationRing A]
  [Field K] [Field L] [Algebra A K] [IsFractionRing A K]
  [Algebra K L] [Algebra A L] [IsScalarTower A K L] [IsGalois K L]
  (Q : Ideal (normalizationCommAlgCat A L).carrier) [Q.IsMaximal]
theorem actualTameCharacter_projection
    (n : actualFiniteTameDegreeSet A K L Q)
    (σ : (actualNormalizationInertiaGroup A K L Q).carrier) :
    (actualFiniteTameRootsSystem A K L Q).projection n
        ((actualTameCharacter A K L Q).toFun σ) =
      (actualTameCoordinate A K L Q n).toFun σ