Module

Conjugation.lean

Nyll.ClassFieldTheory.GlobalClassFieldTheory.Reciprocity.FinitePlaceArtin.Conjugation
8 declarations indexed from sourceView source ↗

Conjugation of finite-place Artin homomorphisms

This module identifies localized completions associated with conjugate extensions and proves conjugation invariance of the resulting finite-place Artin map.

Declarations

GlobalClassFieldTheory.Reciprocity.finitePlaceConjugateLocalizedCompletionAlgEquiv

The algebraic localizations belonging to conjugate extensions of a finite place are identified by the induced equivalence of completions.

Source context 10 commands

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

open scoped IsMulCommutative NNReal NumberField
open NumberField IsDedekindDomain
noncomputable section
namespace GlobalClassFieldTheory
namespace Reciprocity
open AlgebraicNumberTheory.Valuations
open HilbertRamification
open LocalClassFieldTheory
open LocalFieldTheory
variable {K L : Type}
    [Field K] [NumberField K]
    [Field L] [Algebra K L]
    [FiniteDimensional K L] [IsAbelianGalois K L]
def finitePlaceConjugateLocalizedCompletionAlgEquiv
    (v : HeightOneSpectrum (𝓞 K))
    (w : AbsoluteValueExtension
      (NumberField.HeightOneSpectrum.adicAbv K v) L)
    (g : L ≃ₐ[K] L) :
    let vK := NumberField.HeightOneSpectrum.adicAbv K v
    let wc := absoluteValueExtensionConjugate vK w g
    let Ew := AlgebraicNumberTheory.Valuations.LocalizedCompletion vK w
    let Ewc := AlgebraicNumberTheory.Valuations.LocalizedCompletion vK wc
    letI : Algebra vK.Completion Ew :=
      finitePlaceLocalArtinLocalizedAlgebra v w
    letI : Algebra vK.Completion Ewc :=
      finitePlaceLocalArtinLocalizedAlgebra v wc
    Ewc ≃ₐ[vK.Completion] Ew := by
  let vK := NumberField.HeightOneSpectrum.adicAbv K v
  let wc := absoluteValueExtensionConjugate vK w g
  let hvK : vK.IsNontrivial :=
    RayClass.adicAbv_isNontrivial v
  letI hwK :=
    AbsoluteValue.extensionCompletionAlgebra
      (K := K) w.1
  letI : SMul K w.1.Completion := hwK.toSMul
  letI : Algebra vK.Completion w.1.Completion :=
    AbsoluteValue.completionAlgebra vK w.1 w.2
  letI hwcK :=
    AbsoluteValue.extensionCompletionAlgebra
      (K := K) wc.1
  letI : SMul K wc.1.Completion := hwcK.toSMul
  letI : Algebra vK.Completion wc.1.Completion :=
    AbsoluteValue.completionAlgebra vK wc.1 wc.2
  let Ew := AlgebraicNumberTheory.Valuations.LocalizedCompletion vK w
  let Ewc := AlgebraicNumberTheory.Valuations.LocalizedCompletion vK wc
  let eCompletion : wc.1.Completion ≃ₐ[vK.Completion]
      w.1.Completion :=
    { LocalClassFieldTheory.conjugateExtensionCompletionRingEquiv
        vK w g with
      commutes' :=
        LocalClassFieldTheory.conjugateExtensionCompletionRingEquiv_algebraMap
          vK w g }
  let e : Ewc ≃ₐ[vK.Completion] Ew :=
    (AlgebraicNumberTheory.Valuations.localizedCompletionEquivCompletion
        vK hvK wc).trans
      (eCompletion.trans
        (AlgebraicNumberTheory.Valuations.localizedCompletionEquivCompletion
          vK hvK w).symm)
  exact e
GlobalClassFieldTheory.Reciprocity.finitePlaceConjugateLocalizedCompletionAlgEquiv_toAlgebraicLocalization

The conjugate-localization equivalence carries the canonical embedding of L to the conjugate of that embedding.

Source context 11 commands

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

open scoped IsMulCommutative NNReal NumberField
open NumberField IsDedekindDomain
noncomputable section
namespace GlobalClassFieldTheory
namespace Reciprocity
open AlgebraicNumberTheory.Valuations
open HilbertRamification
open LocalClassFieldTheory
open LocalFieldTheory
variable {K L : Type}
    [Field K] [NumberField K]
    [Field L] [Algebra K L]
    [FiniteDimensional K L] [IsAbelianGalois K L]
omit [IsAbelianGalois K L] in
theorem finitePlaceConjugateLocalizedCompletionAlgEquiv_toAlgebraicLocalization
    (v : HeightOneSpectrum (𝓞 K))
    (w : AbsoluteValueExtension
      (NumberField.HeightOneSpectrum.adicAbv K v) L)
    (g : L ≃ₐ[K] L) (x : L) :
    let vK := NumberField.HeightOneSpectrum.adicAbv K v
    let wc := absoluteValueExtensionConjugate vK w g
    let Ew := AlgebraicNumberTheory.Valuations.LocalizedCompletion vK w
    let Ewc := AlgebraicNumberTheory.Valuations.LocalizedCompletion vK wc
    letI : Algebra vK.Completion Ew :=
      finitePlaceLocalArtinLocalizedAlgebra v w
    letI : Algebra vK.Completion Ewc :=
      finitePlaceLocalArtinLocalizedAlgebra v wc
    finitePlaceConjugateLocalizedCompletionAlgEquiv
        (K := K) (L := L) v w g
        (AbsoluteValue.toAlgebraicLocalization
          vK wc.1 wc.2 x) =
      AbsoluteValue.toAlgebraicLocalization
        vK w.1 w.2 (g x) := by
  let vK := NumberField.HeightOneSpectrum.adicAbv K v
  let wc := absoluteValueExtensionConjugate vK w g
  let hvK : vK.IsNontrivial :=
    RayClass.adicAbv_isNontrivial v
  let hwK :=
    AbsoluteValue.extensionCompletionAlgebra
      (K := K) w.1
  let : SMul K w.1.Completion := hwK.toSMul
  let : Algebra vK.Completion w.1.Completion :=
    AbsoluteValue.completionAlgebra vK w.1 w.2
  let hwcK :=
    AbsoluteValue.extensionCompletionAlgebra
      (K := K) wc.1
  let : SMul K wc.1.Completion := hwcK.toSMul
  let : Algebra vK.Completion wc.1.Completion :=
    AbsoluteValue.completionAlgebra vK wc.1 wc.2
  apply
    (AlgebraicNumberTheory.Valuations.localizedCompletionEquivCompletion
      vK hvK w).injective
  change
    LocalClassFieldTheory.conjugateExtensionCompletionRingEquiv
        vK w g
        (AbsoluteValue.toCompletion wc.1 x) =
      AbsoluteValue.toCompletion w.1 (g x)
  exact
    LocalClassFieldTheory.conjugateExtensionCompletionRingEquiv_toCompletion
      vK w g x
GlobalClassFieldTheory.Reciprocity.finitePlaceConjugateLocalizedCompletionAlgEquiv_symm_toAlgebraicLocalization

The inverse conjugate-localization equivalence carries the canonical embedding back along the inverse global automorphism.

Source context 11 commands

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

open scoped IsMulCommutative NNReal NumberField
open NumberField IsDedekindDomain
noncomputable section
namespace GlobalClassFieldTheory
namespace Reciprocity
open AlgebraicNumberTheory.Valuations
open HilbertRamification
open LocalClassFieldTheory
open LocalFieldTheory
variable {K L : Type}
    [Field K] [NumberField K]
    [Field L] [Algebra K L]
    [FiniteDimensional K L] [IsAbelianGalois K L]
omit [IsAbelianGalois K L] in
theorem
    finitePlaceConjugateLocalizedCompletionAlgEquiv_symm_toAlgebraicLocalization
    (v : HeightOneSpectrum (𝓞 K))
    (w : AbsoluteValueExtension
      (NumberField.HeightOneSpectrum.adicAbv K v) L)
    (g : L ≃ₐ[K] L) (x : L) :
    let vK := NumberField.HeightOneSpectrum.adicAbv K v
    let wc := absoluteValueExtensionConjugate vK w g
    let Ew := AlgebraicNumberTheory.Valuations.LocalizedCompletion vK w
    let Ewc := AlgebraicNumberTheory.Valuations.LocalizedCompletion vK wc
    letI : Algebra vK.Completion Ew :=
      finitePlaceLocalArtinLocalizedAlgebra v w
    letI : Algebra vK.Completion Ewc :=
      finitePlaceLocalArtinLocalizedAlgebra v wc
    (finitePlaceConjugateLocalizedCompletionAlgEquiv
        (K := K) (L := L) v w g).symm
        (AbsoluteValue.toAlgebraicLocalization
          vK w.1 w.2 x) =
      AbsoluteValue.toAlgebraicLocalization
        vK wc.1 wc.2 (g.symm x) := by
  let vK := NumberField.HeightOneSpectrum.adicAbv K v
  let wc := absoluteValueExtensionConjugate vK w g
  let hwK :=
    AbsoluteValue.extensionCompletionAlgebra
      (K := K) w.1
  let : SMul K w.1.Completion := hwK.toSMul
  let : Algebra vK.Completion w.1.Completion :=
    AbsoluteValue.completionAlgebra vK w.1 w.2
  let hwcK :=
    AbsoluteValue.extensionCompletionAlgebra
      (K := K) wc.1
  let : SMul K wc.1.Completion := hwcK.toSMul
  let : Algebra vK.Completion wc.1.Completion :=
    AbsoluteValue.completionAlgebra vK wc.1 wc.2
  let e :=
    finitePlaceConjugateLocalizedCompletionAlgEquiv
      (K := K) (L := L) v w g
  apply e.injective
  rw [e.apply_symm_apply,
    finitePlaceConjugateLocalizedCompletionAlgEquiv_toAlgebraicLocalization,
    g.apply_symm_apply]
GlobalClassFieldTheory.Reciprocity.finitePlaceDecompositionTransport_conjugate_apply

Conjugation of a place intertwines the two localization decomposition-group identifications on each local automorphism.

Source context 10 commands

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

open scoped IsMulCommutative NNReal NumberField
open NumberField IsDedekindDomain
noncomputable section
namespace GlobalClassFieldTheory
namespace Reciprocity
open AlgebraicNumberTheory.Valuations
open HilbertRamification
open LocalClassFieldTheory
open LocalFieldTheory
variable {K L : Type}
    [Field K] [NumberField K]
    [Field L] [Algebra K L]
    [FiniteDimensional K L] [IsAbelianGalois K L]
theorem finitePlaceDecompositionTransport_conjugate_apply
    (v : HeightOneSpectrum (𝓞 K))
    (w : AbsoluteValueExtension
      (NumberField.HeightOneSpectrum.adicAbv K v) L)
    (g : L ≃ₐ[K] L) :
    let vK := NumberField.HeightOneSpectrum.adicAbv K v
    let wc := absoluteValueExtensionConjugate vK w g
    let hvK : vK.IsNontrivial :=
      RayClass.adicAbv_isNontrivial v
    let Ew := AlgebraicNumberTheory.Valuations.LocalizedCompletion vK w
    let Ewc := AlgebraicNumberTheory.Valuations.LocalizedCompletion vK wc
    letI : Algebra vK.Completion Ew :=
      finitePlaceLocalArtinLocalizedAlgebra v w
    letI : Algebra vK.Completion Ewc :=
      finitePlaceLocalArtinLocalizedAlgebra v wc
    let e :=
      finitePlaceConjugateLocalizedCompletionAlgEquiv
        (K := K) (L := L) v w g
    let eDw :
        absoluteValueDecompositionGroup K w.1 ≃*
          (Ew ≃ₐ[vK.Completion] Ew) :=
      decompositionGroupEquivAlgebraicLocalizationAut
        vK hvK w
    let eDwc :
        absoluteValueDecompositionGroup K wc.1 ≃*
          (Ewc ≃ₐ[vK.Completion] Ewc) :=
      decompositionGroupEquivAlgebraicLocalizationAut
        vK hvK wc
    ∀ tauC : Ewc ≃ₐ[vK.Completion] Ewc,
      (absoluteValueDecompositionGroup K wc.1).subtype
          (eDwc.symm tauC) =
        (absoluteValueDecompositionGroup K w.1).subtype
          (eDw.symm (AlgEquiv.autCongr e tauC)) := by
  let vK := NumberField.HeightOneSpectrum.adicAbv K v
  let wc := absoluteValueExtensionConjugate vK w g
  let hvK : vK.IsNontrivial :=
    RayClass.adicAbv_isNontrivial v
  let hwK :=
    AbsoluteValue.extensionCompletionAlgebra
      (K := K) w.1
  let : SMul K w.1.Completion := hwK.toSMul
  let : Algebra vK.Completion w.1.Completion :=
    AbsoluteValue.completionAlgebra vK w.1 w.2
  let hwcK :=
    AbsoluteValue.extensionCompletionAlgebra
      (K := K) wc.1
  let : SMul K wc.1.Completion := hwcK.toSMul
  let : Algebra vK.Completion wc.1.Completion :=
    AbsoluteValue.completionAlgebra vK wc.1 wc.2
  let Ew := AlgebraicNumberTheory.Valuations.LocalizedCompletion vK w
  let Ewc := AlgebraicNumberTheory.Valuations.LocalizedCompletion vK wc
  let e :=
    finitePlaceConjugateLocalizedCompletionAlgEquiv
      (K := K) (L := L) v w g
  let eDw :
      absoluteValueDecompositionGroup K w.1 ≃*
        (Ew ≃ₐ[vK.Completion] Ew) :=
    decompositionGroupEquivAlgebraicLocalizationAut
      vK hvK w
  let eDwc :
      absoluteValueDecompositionGroup K wc.1 ≃*
        (Ewc ≃ₐ[vK.Completion] Ewc) :=
    decompositionGroupEquivAlgebraicLocalizationAut
      vK hvK wc
  change
    ∀ tauC : Ewc ≃ₐ[vK.Completion] Ewc,
      (absoluteValueDecompositionGroup K wc.1).subtype
          (eDwc.symm tauC) =
        (absoluteValueDecompositionGroup K w.1).subtype
          (eDw.symm (AlgEquiv.autCongr e tauC))
  intro tauC
  let tau := AlgEquiv.autCongr e tauC
  let rhoC : absoluteValueDecompositionGroup K wc.1 :=
    eDwc.symm tauC
  let rho : absoluteValueDecompositionGroup K w.1 :=
    eDw.symm tau
  change (rhoC.1 : L ≃ₐ[K] L) =
    (rho.1 : L ≃ₐ[K] L)
  apply AlgEquiv.ext
  intro z
  apply
    (AbsoluteValue.toAlgebraicLocalization
      vK w.1 w.2).injective
  have hcomm :
      g ((rhoC.1 : L ≃ₐ[K] L) (g.symm z)) =
        (rhoC.1 : L ≃ₐ[K] L) z := by
    have hg :
        g * (rhoC.1 : L ≃ₐ[K] L) =
          (rhoC.1 : L ≃ₐ[K] L) * g :=
      (inferInstance :
        IsMulCommutative (L ≃ₐ[K] L)).is_comm.comm _ _
    calc
      g ((rhoC.1 : L ≃ₐ[K] L) (g.symm z)) =
          (g * (rhoC.1 : L ≃ₐ[K] L)) (g.symm z) := rfl
      _ = ((rhoC.1 : L ≃ₐ[K] L) * g) (g.symm z) :=
        DFunLike.congr_fun hg (g.symm z)
      _ = (rhoC.1 : L ≃ₐ[K] L) (g (g.symm z)) := rfl
      _ = (rhoC.1 : L ≃ₐ[K] L) z := by
        rw [g.apply_symm_apply]
  calc
    AbsoluteValue.toAlgebraicLocalization vK w.1 w.2
        ((rhoC.1 : L ≃ₐ[K] L) z) =
      AbsoluteValue.toAlgebraicLocalization vK w.1 w.2
        (g ((rhoC.1 : L ≃ₐ[K] L) (g.symm z))) := by
          rw [hcomm]
    _ = e
        (AbsoluteValue.toAlgebraicLocalization vK wc.1 wc.2
          ((rhoC.1 : L ≃ₐ[K] L) (g.symm z))) := by
          rw [
            finitePlaceConjugateLocalizedCompletionAlgEquiv_toAlgebraicLocalization]
    _ = e
        (eDwc rhoC
          (AbsoluteValue.toAlgebraicLocalization
            vK wc.1 wc.2 (g.symm z))) := by
          rw [localizationRamificationGroups_decompositionGroupEquiv_toLocalization]
    _ = e
        (tauC
          (AbsoluteValue.toAlgebraicLocalization
            vK wc.1 wc.2 (g.symm z))) := by
          rw [eDwc.apply_symm_apply]
    _ = (AlgEquiv.autCongr e tauC)
        (AbsoluteValue.toAlgebraicLocalization
          vK w.1 w.2 z) := by
          change
            e
                (tauC
                  (AbsoluteValue.toAlgebraicLocalization
                    vK wc.1 wc.2 (g.symm z))) =
              e
                (tauC
                  (e.symm
                    (AbsoluteValue.toAlgebraicLocalization
                      vK w.1 w.2 z)))
          rw [
            finitePlaceConjugateLocalizedCompletionAlgEquiv_symm_toAlgebraicLocalization]
    _ = tau
        (AbsoluteValue.toAlgebraicLocalization
          vK w.1 w.2 z) := by
          rfl
    _ = eDw rho
        (AbsoluteValue.toAlgebraicLocalization
          vK w.1 w.2 z) := by
          rw [eDw.apply_symm_apply]
    _ = AbsoluteValue.toAlgebraicLocalization vK w.1 w.2
        ((rho.1 : L ≃ₐ[K] L) z) := by
          rw [localizationRamificationGroups_decompositionGroupEquiv_toLocalization]
GlobalClassFieldTheory.Reciprocity.finitePlaceDecompositionTransport_conjugate

Conjugation of a place intertwines the two localization decomposition-group identifications after inclusion in the global Galois group.

Source context 10 commands

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

open scoped IsMulCommutative NNReal NumberField
open NumberField IsDedekindDomain
noncomputable section
namespace GlobalClassFieldTheory
namespace Reciprocity
open AlgebraicNumberTheory.Valuations
open HilbertRamification
open LocalClassFieldTheory
open LocalFieldTheory
variable {K L : Type}
    [Field K] [NumberField K]
    [Field L] [Algebra K L]
    [FiniteDimensional K L] [IsAbelianGalois K L]
theorem finitePlaceDecompositionTransport_conjugate
    (v : HeightOneSpectrum (𝓞 K))
    (w : AbsoluteValueExtension
      (NumberField.HeightOneSpectrum.adicAbv K v) L)
    (g : L ≃ₐ[K] L) :
    let vK := NumberField.HeightOneSpectrum.adicAbv K v
    let wc := absoluteValueExtensionConjugate vK w g
    let hvK : vK.IsNontrivial :=
      RayClass.adicAbv_isNontrivial v
    let Ew := AlgebraicNumberTheory.Valuations.LocalizedCompletion vK w
    let Ewc := AlgebraicNumberTheory.Valuations.LocalizedCompletion vK wc
    letI : Algebra vK.Completion Ew :=
      finitePlaceLocalArtinLocalizedAlgebra v w
    letI : Algebra vK.Completion Ewc :=
      finitePlaceLocalArtinLocalizedAlgebra v wc
    let e :=
      finitePlaceConjugateLocalizedCompletionAlgEquiv
        (K := K) (L := L) v w g
    let eDw :
        absoluteValueDecompositionGroup K w.1 ≃*
          (Ew ≃ₐ[vK.Completion] Ew) :=
      decompositionGroupEquivAlgebraicLocalizationAut
        vK hvK w
    let eDwc :
        absoluteValueDecompositionGroup K wc.1 ≃*
          (Ewc ≃ₐ[vK.Completion] Ewc) :=
      decompositionGroupEquivAlgebraicLocalizationAut
        vK hvK wc
    (absoluteValueDecompositionGroup K wc.1).subtype.comp
        eDwc.symm.toMonoidHom =
      ((absoluteValueDecompositionGroup K w.1).subtype.comp
          eDw.symm.toMonoidHom).comp
        (AlgEquiv.autCongr e).toMonoidHom := by
  apply MonoidHom.ext
  intro tauC
  exact
    finitePlaceDecompositionTransport_conjugate_apply
      (K := K) (L := L) v w g tauC
GlobalClassFieldTheory.Reciprocity.finitePlaceLocalArtinMonoidHom_conjugate

Local Artin maps are natural under the localized-completion equivalence induced by conjugating a finite-place extension.

Source context 10 commands

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

open scoped IsMulCommutative NNReal NumberField
open NumberField IsDedekindDomain
noncomputable section
namespace GlobalClassFieldTheory
namespace Reciprocity
open AlgebraicNumberTheory.Valuations
open HilbertRamification
open LocalClassFieldTheory
open LocalFieldTheory
variable {K L : Type}
    [Field K] [NumberField K]
    [Field L] [Algebra K L]
    [FiniteDimensional K L] [IsAbelianGalois K L]
theorem finitePlaceLocalArtinMonoidHom_conjugate
    (v : HeightOneSpectrum (𝓞 K))
    (w : AbsoluteValueExtension
      (NumberField.HeightOneSpectrum.adicAbv K v) L)
    (g : L ≃ₐ[K] L) :
    let vK := NumberField.HeightOneSpectrum.adicAbv K v
    let wc := absoluteValueExtensionConjugate vK w g
    let Ew := AlgebraicNumberTheory.Valuations.LocalizedCompletion vK w
    let Ewc := AlgebraicNumberTheory.Valuations.LocalizedCompletion vK wc
    letI : Algebra vK.Completion Ew :=
      finitePlaceLocalArtinLocalizedAlgebra v w
    letI : Algebra vK.Completion Ewc :=
      finitePlaceLocalArtinLocalizedAlgebra v wc
    let e :=
      finitePlaceConjugateLocalizedCompletionAlgEquiv
        (K := K) (L := L) v w g
    (AlgEquiv.autCongr e).toMonoidHom.comp
        (finitePlaceLocalArtinMonoidHom
          (K := K) (L := L) v wc) =
      finitePlaceLocalArtinMonoidHom
        (K := K) (L := L) v w := by
  let vK := NumberField.HeightOneSpectrum.adicAbv K v
  let wc := absoluteValueExtensionConjugate vK w g
  let Ew := AlgebraicNumberTheory.Valuations.LocalizedCompletion vK w
  let Ewc := AlgebraicNumberTheory.Valuations.LocalizedCompletion vK wc
  let : Algebra vK.Completion Ew :=
    finitePlaceLocalArtinLocalizedAlgebra v w
  let : Algebra vK.Completion Ewc :=
    finitePlaceLocalArtinLocalizedAlgebra v wc
  let : FiniteDimensional vK.Completion Ew :=
    finitePlaceLocalArtinFiniteDimensional v w
  let : FiniteDimensional vK.Completion Ewc :=
    finitePlaceLocalArtinFiniteDimensional v wc
  let : IsAbelianGalois vK.Completion Ew :=
    finitePlaceLocalArtinIsAbelianGalois v w
      (inferInstance : FiniteDimensional K L)
  let : IsAbelianGalois vK.Completion Ewc :=
    finitePlaceLocalArtinIsAbelianGalois v wc
      (inferInstance : FiniteDimensional K L)
  let : ValuativeRel vK.Completion :=
    finitePlaceLocalArtinCompletionValuativeRel v
  let : IsNonarchimedeanLocalField vK.Completion :=
    finitePlaceLocalArtinCompletionIsNonarchimedeanLocalField v
  let e :=
    finitePlaceConjugateLocalizedCompletionAlgEquiv
      (K := K) (L := L) v w g
  let eK :
      vK.Completionˣ ≃* (v.adicCompletion K)ˣ :=
    finitePlaceCompletionUnitsContinuousMulEquiv v
  change
    (AlgEquiv.autCongr e).toMonoidHom.comp
        ((LocalClassFieldTheory.abelianLocalArtinMonoidHom
          vK.Completion Ewc).comp eK.symm.toMonoidHom) =
      (LocalClassFieldTheory.abelianLocalArtinMonoidHom
        vK.Completion Ew).comp eK.symm.toMonoidHom
  exact
    congrArg (fun f => f.comp eK.symm.toMonoidHom)
      (LocalClassFieldTheory.abelianLocalArtinMonoidHom_autCongr
        vK.Completion Ewc Ew e)
GlobalClassFieldTheory.Reciprocity.finitePlaceArtinMonoidHomOfExtension_conjugate

Conjugating the chosen extension of a finite place does not change its Artin homomorphism when the global extension is abelian.

Source context 10 commands

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

open scoped IsMulCommutative NNReal NumberField
open NumberField IsDedekindDomain
noncomputable section
namespace GlobalClassFieldTheory
namespace Reciprocity
open AlgebraicNumberTheory.Valuations
open HilbertRamification
open LocalClassFieldTheory
open LocalFieldTheory
variable {K L : Type}
    [Field K] [NumberField K]
    [Field L] [Algebra K L]
    [FiniteDimensional K L] [IsAbelianGalois K L]
theorem finitePlaceArtinMonoidHomOfExtension_conjugate
    (v : HeightOneSpectrum (𝓞 K))
    (w : AbsoluteValueExtension
      (NumberField.HeightOneSpectrum.adicAbv K v) L)
    (g : L ≃ₐ[K] L) :
    finitePlaceArtinMonoidHomOfExtension
        (K := K) (L := L) v
        (absoluteValueExtensionConjugate
          (NumberField.HeightOneSpectrum.adicAbv K v) w g) =
      finitePlaceArtinMonoidHomOfExtension
        (K := K) (L := L) v w
GlobalClassFieldTheory.Reciprocity.finitePlaceArtinMonoidHomOfExtension_eq

The finite-place Artin homomorphism is independent of the chosen extension of the base place in an abelian extension.

Source context 10 commands

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

open scoped IsMulCommutative NNReal NumberField
open NumberField IsDedekindDomain
noncomputable section
namespace GlobalClassFieldTheory
namespace Reciprocity
open AlgebraicNumberTheory.Valuations
open HilbertRamification
open LocalClassFieldTheory
open LocalFieldTheory
variable {K L : Type}
    [Field K] [NumberField K]
    [Field L] [Algebra K L]
    [FiniteDimensional K L] [IsAbelianGalois K L]
theorem finitePlaceArtinMonoidHomOfExtension_eq
    (v : HeightOneSpectrum (𝓞 K))
    (w w' : AbsoluteValueExtension
      (NumberField.HeightOneSpectrum.adicAbv K v) L) :
    finitePlaceArtinMonoidHomOfExtension
        (K := K) (L := L) v w =
      finitePlaceArtinMonoidHomOfExtension
        (K := K) (L := L) v w'