Module

FiniteAbelianLocalReciprocityFamilyExt.lean

Nyll.ClassFieldTheory.Theorems.LocalClassFieldTheory.FiniteAbelianLocalReciprocityFamilyExt
1 declaration indexed from sourceView source ↗

Uniqueness of the normalized coherent local Artin family

Norm kernels and tower compatibility alone leave an orientation ambiguity at finite levels. Arithmetic Frobenius on unramified extensions removes it for the entire coherent family, including ramified extensions.

Declarations

ClassFieldTheory.finiteAbelianLocalReciprocity_family_ext

A coherent family of finite local Artin maps is uniquely determined by its norm kernels and its arithmetic-Frobenius normalization. The chosen uniformizer is only used to express that normalization; the conclusion does not depend on it.

Source context 3 commands

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

open scoped ValuativeRel
noncomputable section
namespace ClassFieldTheory
theorem finiteAbelianLocalReciprocity_family_ext
    (K : Type) [Field K] [ValuativeRel K] [TopologicalSpace K]
    [IsNonarchimedeanLocalField K]
    (f g : (E : FiniteAbelianLocalExtension K) →
      Kˣ →ₜ* (E.1 ≃ₐ[K] E.1))
    (hfker : ∀ E : FiniteAbelianLocalExtension K,
      (f E).toMonoidHom.ker = E.normSubgroup)
    (hgker : ∀ E : FiniteAbelianLocalExtension K,
      (g E).toMonoidHom.ker = E.normSubgroup)
    (hfcoh : ∀ (E F : FiniteAbelianLocalExtension K)
      (hEF : E.1 ≤ F.1) (x : Kˣ) (y : E.1),
      IntermediateField.inclusion hEF ((f E x) y) =
        (f F x) (IntermediateField.inclusion hEF y))
    (hgcoh : ∀ (E F : FiniteAbelianLocalExtension K)
      (hEF : E.1 ≤ F.1) (x : Kˣ) (y : E.1),
      IntermediateField.inclusion hEF ((g E x) y) =
        (g F x) (IntermediateField.inclusion hEF y))
    (hfrob : ∀ (E : FiniteAbelianLocalExtension K)
      [ValuativeRel E.1] [UniformSpace E.1] [IsUniformAddGroup E.1]
      [IsNonarchimedeanLocalField E.1]
      [Valuation.HasExtension (ValuativeRel.valuation K)
        (ValuativeRel.valuation E.1)],
      (𝓂[E.1] : Ideal 𝒪[E.1]).ramificationIdx 𝒪[K] = 1 →
      ∀ (π : 𝒪[K])
        (hπ : (ValuativeRel.valuation K).IsUniformizer (π : K))
        (x : 𝒪[E.1]),
        ∃ z : 𝒪[E.1],
          (z : E.1) =
            (f E ((Units.mk0 (π : K) hπ.ne_zero)⁻¹)) (x : E.1) ∧
          IsLocalRing.residue 𝒪[E.1] z =
            (IsLocalRing.residue 𝒪[E.1] x) ^ Nat.card 𝓀[K])
    (hgrob : ∀ (E : FiniteAbelianLocalExtension K)
      [ValuativeRel E.1] [UniformSpace E.1] [IsUniformAddGroup E.1]
      [IsNonarchimedeanLocalField E.1]
      [Valuation.HasExtension (ValuativeRel.valuation K)
        (ValuativeRel.valuation E.1)],
      (𝓂[E.1] : Ideal 𝒪[E.1]).ramificationIdx 𝒪[K] = 1 →
      ∀ (π : 𝒪[K])
        (hπ : (ValuativeRel.valuation K).IsUniformizer (π : K))
        (x : 𝒪[E.1]),
        ∃ z : 𝒪[E.1],
          (z : E.1) =
            (g E ((Units.mk0 (π : K) hπ.ne_zero)⁻¹)) (x : E.1) ∧
          IsLocalRing.residue 𝒪[E.1] z =
            (IsLocalRing.residue 𝒪[E.1] x) ^ Nat.card 𝓀[K])
    : f = g