Module

FiniteAbelianLocalReciprocityQuotientEquivMk.lean

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

The local norm quotient is induced by the Artin map

The existence statements for the finite Artin map and the norm-quotient isomorphism alone do not say that their witnesses agree. Here a single canonical Artin map is chosen, and its quotient isomorphism is characterized uniquely by its values on classes of nonzero field elements.

Declarations

ClassFieldTheory.finiteAbelianLocalReciprocity_quotientEquiv_mk

The continuous norm-quotient equivalence is uniquely determined by the canonical finite local Artin map, with the expected value on every class.

Source context 2 commands

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

noncomputable section
namespace ClassFieldTheory
theorem finiteAbelianLocalReciprocity_quotientEquiv_mk
    (K L : Type)
    [Field K] [Field L] [Algebra K L]
    [FiniteDimensional K L] [IsAbelianGalois K L]
    [ValuativeRel K] [TopologicalSpace K]
    [IsNonarchimedeanLocalField K] :
    ∃ artin : Kˣ →ₜ* (L ≃ₐ[K] L),
      Function.Surjective artin ∧
      artin.ker = fieldNormSubgroup K L ∧
      ∃! e : FieldNormQuotient K L ≃ₜ* (L ≃ₐ[K] L),
        ∀ x : Kˣ, e (QuotientGroup.mk' (fieldNormSubgroup K L) x) = artin x