Module

ProfiniteLocalReciprocity.lean

Nyll.ClassFieldTheory.LocalClassFieldTheory.Infinite.ProfiniteLocalReciprocity
33 declarations indexed from sourceView source ↗

Profinite local reciprocity

The absolute Artin map constructed from the compatible finite reciprocity maps is transported from the fixed separable closure to Mathlib's usual algebraic-closure absolute Galois group. Its canonical extension to the topological profinite completion is then automatically onto. Injectivity is supplied by the arithmetic cofinality consequence of the finite local existence theorem.

Declarations

LocalClassFieldTheory.standardToSeparableAbsoluteGaloisEquiv

Restriction to the separable closure gives the canonical topological identification between the usual and separable absolute Galois groups.

Source context 5 commands

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

noncomputable section
open CategoryTheory
namespace LocalClassFieldTheory
open LocalFieldTheory RamificationTheory
variable (K : Type) [Field K] [ValuativeRel K] [TopologicalSpace K]
  [IsNonarchimedeanLocalField K]
def standardToSeparableAbsoluteGaloisEquiv :
    _root_.Field.absoluteGaloisGroup K ≃ₜ* intrinsicAbsoluteGalois K
LocalClassFieldTheory.separableToStandardAbsoluteAbelianizationEquiv

The induced canonical identification from the separable absolute topological abelianization to Mathlib's usual one.

Source context 5 commands

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

noncomputable section
open CategoryTheory
namespace LocalClassFieldTheory
open LocalFieldTheory RamificationTheory
variable (K : Type) [Field K] [ValuativeRel K] [TopologicalSpace K]
  [IsNonarchimedeanLocalField K]
def separableToStandardAbsoluteAbelianizationEquiv :
    TopologicalAbelianization (intrinsicAbsoluteGalois K) ≃ₜ*
      _root_.Field.absoluteGaloisGroupAbelianization K
LocalClassFieldTheory.standardLocalAbsoluteAbelianization_totallyDisconnectedSpace

The separable model makes the standard absolute abelianization totally disconnected.

Source context 5 commands

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

noncomputable section
open CategoryTheory
namespace LocalClassFieldTheory
open LocalFieldTheory RamificationTheory
variable (K : Type) [Field K] [ValuativeRel K] [TopologicalSpace K]
  [IsNonarchimedeanLocalField K]
instance standardLocalAbsoluteAbelianization_totallyDisconnectedSpace :
    TotallyDisconnectedSpace
      (_root_.Field.absoluteGaloisGroupAbelianization K)
LocalClassFieldTheory.standardLocalAbsoluteAbelianization_compactSpace

The standard absolute abelianization is compact via the separable-model equivalence.

Source context 5 commands

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

noncomputable section
open CategoryTheory
namespace LocalClassFieldTheory
open LocalFieldTheory RamificationTheory
variable (K : Type) [Field K] [ValuativeRel K] [TopologicalSpace K]
  [IsNonarchimedeanLocalField K]
instance standardLocalAbsoluteAbelianization_compactSpace :
    CompactSpace (_root_.Field.absoluteGaloisGroupAbelianization K)
LocalClassFieldTheory.standardLocalAbsoluteAbelianization_t2Space

The standard absolute abelianization is Hausdorff via the separable-model equivalence.

Source context 5 commands

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

noncomputable section
open CategoryTheory
namespace LocalClassFieldTheory
open LocalFieldTheory RamificationTheory
variable (K : Type) [Field K] [ValuativeRel K] [TopologicalSpace K]
  [IsNonarchimedeanLocalField K]
instance standardLocalAbsoluteAbelianization_t2Space :
    T2Space (_root_.Field.absoluteGaloisGroupAbelianization K)
LocalClassFieldTheory.standardLocalAbsoluteAbelianProfinite

The usual absolute Galois topological abelianization, packaged as a stable profinite group.

Source context 5 commands

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

noncomputable section
open CategoryTheory
namespace LocalClassFieldTheory
open LocalFieldTheory RamificationTheory
variable (K : Type) [Field K] [ValuativeRel K] [TopologicalSpace K]
  [IsNonarchimedeanLocalField K]
def standardLocalAbsoluteAbelianProfinite
    (K : Type) [Field K] : ProfiniteGrp
LocalClassFieldTheory.separableProfiniteLocalReciprocityHom

The canonical extension of the separable absolute Artin map to the open-finite-quotient completion of the local multiplicative group.

Source context 5 commands

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

noncomputable section
open CategoryTheory
namespace LocalClassFieldTheory
open LocalFieldTheory RamificationTheory
variable (K : Type) [Field K] [ValuativeRel K] [TopologicalSpace K]
  [IsNonarchimedeanLocalField K]
def separableProfiniteLocalReciprocityHom :
    TopologicalProfiniteCompletion Kˣ →ₜ*
      localAbsoluteAbelianProfinite K
LocalClassFieldTheory.separableProfiniteLocalReciprocityHom_map

The separable reciprocity lift agrees with the Artin map on canonical completion points.

Source context 5 commands

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

noncomputable section
open CategoryTheory
namespace LocalClassFieldTheory
open LocalFieldTheory RamificationTheory
variable (K : Type) [Field K] [ValuativeRel K] [TopologicalSpace K]
  [IsNonarchimedeanLocalField K]
theorem separableProfiniteLocalReciprocityHom_map (a : Kˣ) :
    separableProfiniteLocalReciprocityHom K
        (topologicalProfiniteCompletionMap Kˣ a) =
      separableAbsoluteLocalArtinMap K a
LocalClassFieldTheory.separableProfiniteLocalReciprocityHom_comp_completionMap

Composing the separable reciprocity lift with the completion map recovers the Artin map.

Source context 5 commands

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

noncomputable section
open CategoryTheory
namespace LocalClassFieldTheory
open LocalFieldTheory RamificationTheory
variable (K : Type) [Field K] [ValuativeRel K] [TopologicalSpace K]
  [IsNonarchimedeanLocalField K]
theorem separableProfiniteLocalReciprocityHom_comp_completionMap :
    (separableProfiniteLocalReciprocityHom K).comp
        (topologicalProfiniteCompletionMap Kˣ) =
      separableAbsoluteLocalArtinMap K
LocalClassFieldTheory.separableProfiniteLocalReciprocityHom_surjective

The separable profinite reciprocity homomorphism is onto.

Source context 5 commands

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

noncomputable section
open CategoryTheory
namespace LocalClassFieldTheory
open LocalFieldTheory RamificationTheory
variable (K : Type) [Field K] [ValuativeRel K] [TopologicalSpace K]
  [IsNonarchimedeanLocalField K]
theorem separableProfiniteLocalReciprocityHom_surjective :
    Function.Surjective (separableProfiniteLocalReciprocityHom K)
LocalClassFieldTheory.separableProfiniteLocalReciprocityHom_injective

Finite local existence makes the separable profinite reciprocity homomorphism one-to-one.

Source context 5 commands

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

noncomputable section
open CategoryTheory
namespace LocalClassFieldTheory
open LocalFieldTheory RamificationTheory
variable (K : Type) [Field K] [ValuativeRel K] [TopologicalSpace K]
  [IsNonarchimedeanLocalField K]
theorem separableProfiniteLocalReciprocityHom_injective :
    Function.Injective (separableProfiniteLocalReciprocityHom K)
LocalClassFieldTheory.separableProfiniteLocalReciprocity

Profinite local reciprocity for the fixed separable closure.

Source context 5 commands

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

noncomputable section
open CategoryTheory
namespace LocalClassFieldTheory
open LocalFieldTheory RamificationTheory
variable (K : Type) [Field K] [ValuativeRel K] [TopologicalSpace K]
  [IsNonarchimedeanLocalField K]
def separableProfiniteLocalReciprocity :
    TopologicalProfiniteCompletion Kˣ ≃ₜ*
      localAbsoluteAbelianProfinite K
LocalClassFieldTheory.separableProfiniteLocalReciprocity_apply

The separable reciprocity equivalence has the same underlying map as its lifted homomorphism.

Source context 5 commands

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

noncomputable section
open CategoryTheory
namespace LocalClassFieldTheory
open LocalFieldTheory RamificationTheory
variable (K : Type) [Field K] [ValuativeRel K] [TopologicalSpace K]
  [IsNonarchimedeanLocalField K]
theorem separableProfiniteLocalReciprocity_apply
    (x : TopologicalProfiniteCompletion Kˣ) :
    separableProfiniteLocalReciprocity K x =
      separableProfiniteLocalReciprocityHom K x
LocalClassFieldTheory.separableToStandardAbsoluteAbelianizationHom

The forward transport from the separable to the usual absolute topological abelianization, as a continuous homomorphism.

Source context 5 commands

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

noncomputable section
open CategoryTheory
namespace LocalClassFieldTheory
open LocalFieldTheory RamificationTheory
variable (K : Type) [Field K] [ValuativeRel K] [TopologicalSpace K]
  [IsNonarchimedeanLocalField K]
def separableToStandardAbsoluteAbelianizationHom :
    localAbsoluteAbelianProfinite K →ₜ*
      standardLocalAbsoluteAbelianProfinite K
LocalClassFieldTheory.absoluteLocalArtinMap

The absolute local Artin map with Mathlib's usual algebraic-closure absolute Galois group as target.

Source context 5 commands

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

noncomputable section
open CategoryTheory
namespace LocalClassFieldTheory
open LocalFieldTheory RamificationTheory
variable (K : Type) [Field K] [ValuativeRel K] [TopologicalSpace K]
  [IsNonarchimedeanLocalField K]
def absoluteLocalArtinMap :
    Kˣ →ₜ* standardLocalAbsoluteAbelianProfinite K
LocalClassFieldTheory.separableToStandardAbsoluteAbelianizationEquiv_symm_artinMap

Transporting the separable Artin map to the standard model gives the absolute Artin map.

Source context 5 commands

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

noncomputable section
open CategoryTheory
namespace LocalClassFieldTheory
open LocalFieldTheory RamificationTheory
variable (K : Type) [Field K] [ValuativeRel K] [TopologicalSpace K]
  [IsNonarchimedeanLocalField K]
theorem separableToStandardAbsoluteAbelianizationEquiv_symm_artinMap
    (a : Kˣ) :
    (separableToStandardAbsoluteAbelianizationEquiv K).symm
        (absoluteLocalArtinMap K a) =
      separableAbsoluteLocalArtinMap K a
LocalClassFieldTheory.absoluteLocalArtinMap_denseRange

The usual absolute local Artin map has dense image.

Source context 5 commands

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

noncomputable section
open CategoryTheory
namespace LocalClassFieldTheory
open LocalFieldTheory RamificationTheory
variable (K : Type) [Field K] [ValuativeRel K] [TopologicalSpace K]
  [IsNonarchimedeanLocalField K]
theorem absoluteLocalArtinMap_denseRange :
    DenseRange (absoluteLocalArtinMap K)
LocalClassFieldTheory.profiniteLocalReciprocityHom

The canonical homomorphism from the topological profinite completion of K× to the usual absolute Galois topological abelianization.

Source context 5 commands

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

noncomputable section
open CategoryTheory
namespace LocalClassFieldTheory
open LocalFieldTheory RamificationTheory
variable (K : Type) [Field K] [ValuativeRel K] [TopologicalSpace K]
  [IsNonarchimedeanLocalField K]
def profiniteLocalReciprocityHom :
    TopologicalProfiniteCompletion Kˣ →ₜ*
      standardLocalAbsoluteAbelianProfinite K
LocalClassFieldTheory.profiniteLocalReciprocityHom_map

The standard reciprocity lift agrees with the absolute Artin map on canonical completion points.

Source context 5 commands

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

noncomputable section
open CategoryTheory
namespace LocalClassFieldTheory
open LocalFieldTheory RamificationTheory
variable (K : Type) [Field K] [ValuativeRel K] [TopologicalSpace K]
  [IsNonarchimedeanLocalField K]
theorem profiniteLocalReciprocityHom_map (a : Kˣ) :
    profiniteLocalReciprocityHom K
        (topologicalProfiniteCompletionMap Kˣ a) =
      absoluteLocalArtinMap K a
LocalClassFieldTheory.profiniteLocalReciprocityHom_comp_completionMap

The profinite reciprocity homomorphism extends the absolute Artin map.

Source context 5 commands

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

noncomputable section
open CategoryTheory
namespace LocalClassFieldTheory
open LocalFieldTheory RamificationTheory
variable (K : Type) [Field K] [ValuativeRel K] [TopologicalSpace K]
  [IsNonarchimedeanLocalField K]
theorem profiniteLocalReciprocityHom_comp_completionMap :
    (profiniteLocalReciprocityHom K).comp
        (topologicalProfiniteCompletionMap Kˣ) =
      absoluteLocalArtinMap K
LocalClassFieldTheory.profiniteLocalReciprocityHom_surjective

Dense range of the absolute Artin map and compactness of the completion make the profinite reciprocity homomorphism onto.

Source context 5 commands

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

noncomputable section
open CategoryTheory
namespace LocalClassFieldTheory
open LocalFieldTheory RamificationTheory
variable (K : Type) [Field K] [ValuativeRel K] [TopologicalSpace K]
  [IsNonarchimedeanLocalField K]
theorem profiniteLocalReciprocityHom_surjective :
    Function.Surjective (profiniteLocalReciprocityHom K)
LocalClassFieldTheory.profiniteLocalReciprocityHom_finiteProjection_map

Finite target projections agree with projection of the absolute Artin map on the dense copy of K×.

Source context 5 commands

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

noncomputable section
open CategoryTheory
namespace LocalClassFieldTheory
open LocalFieldTheory RamificationTheory
variable (K : Type) [Field K] [ValuativeRel K] [TopologicalSpace K]
  [IsNonarchimedeanLocalField K]
theorem profiniteLocalReciprocityHom_finiteProjection_map
    (N : OpenNormalSubgroup (standardLocalAbsoluteAbelianProfinite K))
    (a : Kˣ) :
    topologicalProfiniteCompletionFiniteProjection
        (standardLocalAbsoluteAbelianProfinite K) (absoluteLocalArtinMap K) N
        (topologicalProfiniteCompletionMap Kˣ a) =
      QuotientGroup.mk' N.toSubgroup (absoluteLocalArtinMap K a)
LocalClassFieldTheory.profiniteLocalReciprocityHom_unique

The profinite reciprocity homomorphism is the unique continuous homomorphism extending the absolute local Artin map.

Source context 5 commands

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

noncomputable section
open CategoryTheory
namespace LocalClassFieldTheory
open LocalFieldTheory RamificationTheory
variable (K : Type) [Field K] [ValuativeRel K] [TopologicalSpace K]
  [IsNonarchimedeanLocalField K]
theorem profiniteLocalReciprocityHom_unique
    (f : TopologicalProfiniteCompletion Kˣ →ₜ*
      standardLocalAbsoluteAbelianProfinite K)
    (hf : f.comp (topologicalProfiniteCompletionMap Kˣ) =
      absoluteLocalArtinMap K) :
    f = profiniteLocalReciprocityHom K
LocalClassFieldTheory.profiniteLocalReciprocityHom_eq_transport

The canonical lift to the usual absolute abelianization is transport of the corresponding separable lift.

Source context 5 commands

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

noncomputable section
open CategoryTheory
namespace LocalClassFieldTheory
open LocalFieldTheory RamificationTheory
variable (K : Type) [Field K] [ValuativeRel K] [TopologicalSpace K]
  [IsNonarchimedeanLocalField K]
theorem profiniteLocalReciprocityHom_eq_transport :
    profiniteLocalReciprocityHom K =
      (separableToStandardAbsoluteAbelianizationHom K).comp
        (separableProfiniteLocalReciprocityHom K)
LocalClassFieldTheory.profiniteLocalReciprocityHom_injective

The canonical lift to the usual absolute abelianization is one-to-one.

Source context 5 commands

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

noncomputable section
open CategoryTheory
namespace LocalClassFieldTheory
open LocalFieldTheory RamificationTheory
variable (K : Type) [Field K] [ValuativeRel K] [TopologicalSpace K]
  [IsNonarchimedeanLocalField K]
theorem profiniteLocalReciprocityHom_injective :
    Function.Injective (profiniteLocalReciprocityHom K)
LocalClassFieldTheory.profiniteLocalReciprocity

Profinite local reciprocity. The topological profinite completion of the local multiplicative group is canonically continuously isomorphic to the topological abelianization of Mathlib's usual absolute Galois group.

Source context 5 commands

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

noncomputable section
open CategoryTheory
namespace LocalClassFieldTheory
open LocalFieldTheory RamificationTheory
variable (K : Type) [Field K] [ValuativeRel K] [TopologicalSpace K]
  [IsNonarchimedeanLocalField K]
def profiniteLocalReciprocity :
    TopologicalProfiniteCompletion Kˣ ≃ₜ*
      standardLocalAbsoluteAbelianProfinite K
LocalClassFieldTheory.profiniteLocalReciprocity_apply

The standard reciprocity equivalence has the same underlying map as its lifted homomorphism.

Source context 5 commands

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

noncomputable section
open CategoryTheory
namespace LocalClassFieldTheory
open LocalFieldTheory RamificationTheory
variable (K : Type) [Field K] [ValuativeRel K] [TopologicalSpace K]
  [IsNonarchimedeanLocalField K]
theorem profiniteLocalReciprocity_apply
    (x : TopologicalProfiniteCompletion Kˣ) :
    profiniteLocalReciprocity K x =
      profiniteLocalReciprocityHom K x
LocalClassFieldTheory.profiniteLocalReciprocity_completionMap

Profinite reciprocity restricts to the absolute local Artin map on the dense copy of the local multiplicative group.

Source context 5 commands

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

noncomputable section
open CategoryTheory
namespace LocalClassFieldTheory
open LocalFieldTheory RamificationTheory
variable (K : Type) [Field K] [ValuativeRel K] [TopologicalSpace K]
  [IsNonarchimedeanLocalField K]
theorem profiniteLocalReciprocity_completionMap (a : Kˣ) :
    profiniteLocalReciprocity K
        (topologicalProfiniteCompletionMap Kˣ a) =
      absoluteLocalArtinMap K a
LocalClassFieldTheory.absoluteLocalArtinMap_injective

The absolute local Artin map is injective.

Source context 5 commands

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

noncomputable section
open CategoryTheory
namespace LocalClassFieldTheory
open LocalFieldTheory RamificationTheory
variable (K : Type) [Field K] [ValuativeRel K] [TopologicalSpace K]
  [IsNonarchimedeanLocalField K]
theorem absoluteLocalArtinMap_injective :
    Function.Injective (absoluteLocalArtinMap K)
LocalClassFieldTheory.profiniteLocalReciprocity_finiteProjection

Every finite quotient projection of profinite reciprocity is the finite projection canonically induced by the absolute local Artin map.

Source context 5 commands

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

noncomputable section
open CategoryTheory
namespace LocalClassFieldTheory
open LocalFieldTheory RamificationTheory
variable (K : Type) [Field K] [ValuativeRel K] [TopologicalSpace K]
  [IsNonarchimedeanLocalField K]
theorem profiniteLocalReciprocity_finiteProjection
    (N : OpenNormalSubgroup (standardLocalAbsoluteAbelianProfinite K))
    (x : TopologicalProfiniteCompletion Kˣ) :
    QuotientGroup.mk' N.toSubgroup (profiniteLocalReciprocity K x) =
      topologicalProfiniteCompletionFiniteProjection
        (standardLocalAbsoluteAbelianProfinite K) (absoluteLocalArtinMap K) N x
LocalClassFieldTheory.profiniteLocalReciprocity_unique

Profinite local reciprocity is the unique continuous multiplicative equivalence whose composite with the completion map is the absolute Artin map.

Source context 5 commands

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

noncomputable section
open CategoryTheory
namespace LocalClassFieldTheory
open LocalFieldTheory RamificationTheory
variable (K : Type) [Field K] [ValuativeRel K] [TopologicalSpace K]
  [IsNonarchimedeanLocalField K]
theorem profiniteLocalReciprocity_unique
    (e : TopologicalProfiniteCompletion Kˣ ≃ₜ*
      standardLocalAbsoluteAbelianProfinite K)
    (he : (ContinuousMonoidHom.toContinuousMonoidHom e).comp
        (topologicalProfiniteCompletionMap Kˣ) =
      absoluteLocalArtinMap K) :
    e = profiniteLocalReciprocity K
LocalClassFieldTheory.standardAbsoluteGaloisAbelianizationLimitEquiv

Mathlib's absolute Galois abelianization is canonically the inverse limit of its finite quotients, after transport from the fixed separable closure.

Source context 5 commands

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

noncomputable section
open CategoryTheory
namespace LocalClassFieldTheory
open LocalFieldTheory RamificationTheory
variable (K : Type) [Field K] [ValuativeRel K] [TopologicalSpace K]
  [IsNonarchimedeanLocalField K]
def standardAbsoluteGaloisAbelianizationLimitEquiv :
    ContinuousMulEquiv (standardLocalAbsoluteAbelianProfinite K)
      (absoluteFiniteArtinLimit K)
LocalClassFieldTheory.absoluteLocalArtinMap_finiteProjection

Every finite projection of the absolute Artin map is its corresponding finite local Artin coordinate after canonical transport to the separable closure model.

Source context 5 commands

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

noncomputable section
open CategoryTheory
namespace LocalClassFieldTheory
open LocalFieldTheory RamificationTheory
variable (K : Type) [Field K] [ValuativeRel K] [TopologicalSpace K]
  [IsNonarchimedeanLocalField K]
theorem absoluteLocalArtinMap_finiteProjection
    (N : OpenNormalSubgroup (localAbsoluteAbelianProfinite K))
    (a : Units K) :
    QuotientGroup.mk' N.toSubgroup
        ((separableToStandardAbsoluteAbelianizationEquiv K).symm
          (absoluteLocalArtinMap K a)) =
      absoluteFiniteArtinMap K N a