Module

FixedFieldNormResidueNaturality.lean

Nyll.ClassFieldTheory.LocalClassFieldTheory.Finite.LocalReciprocity.FixedFieldNormResidueNaturality
26 declarations indexed from sourceView source ↗

Naturality of fixed-field norm-residue symbols

This file transports norm-restriction and transfer-inclusion naturality from the closed-subgroup class formation to actual fixed fields in a single Galois ambient field.

Canonical local-field specializations

Declarations

LocalClassFieldTheory.abstractFixedFieldUnitsInclusion

Inclusion of the units of the lower concrete fixed field in the units of the larger concrete fixed field.

Source context 5 commands

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

noncomputable section
namespace LocalClassFieldTheory
open LocalFieldTheory RamificationTheory CyclicCohomology KummerTheory
open ClassFormation LocalClassFieldTheory
variable (k Ω : Type) [Field k] [Field Ω] [Algebra k Ω] [IsGalois k Ω]
def abstractFixedFieldUnitsInclusion
    (K K' : ClosedSubgroup (Gal(Ω/k)))
    (hK'K : K'.toSubgroup ≤ K.toSubgroup) :
    Additive (abstractFixedField k Ω K)ˣ →+
      Additive (abstractFixedField k Ω K')ˣ
LocalClassFieldTheory.abstractFixedFieldUnitsEquiv_inclusion

The concrete fixed-field unit equivalences identify actual unit inclusion with inclusion of fixed coefficients.

Source context 6 commands

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

noncomputable section
namespace LocalClassFieldTheory
open LocalFieldTheory RamificationTheory CyclicCohomology KummerTheory
open ClassFormation LocalClassFieldTheory
variable (k Ω : Type) [Field k] [Field Ω] [Algebra k Ω] [IsGalois k Ω]
omit [IsGalois k Ω] in
theorem abstractFixedFieldUnitsEquiv_inclusion
    (K K' : ClosedSubgroup (Gal(Ω/k)))
    (hK'K : K'.toSubgroup ≤ K.toSubgroup)
    (x : Additive (abstractFixedField k Ω K)ˣ) :
    abstractFixedFieldUnitsEquivGaloisFixed k Ω K'
        (abstractFixedFieldUnitsInclusion k Ω K K' hK'K x) =
      fixedFieldInclusion (galoisAmbientUnitsRep k Ω)
        K K' hK'K
        (abstractFixedFieldUnitsEquivGaloisFixed k Ω K x)
LocalClassFieldTheory.abstractFixedFieldNormResidueSymbol

The norm-residue symbol on the actual units of a concrete fixed field, obtained from the abstract class-formation symbol through the canonical fixed-unit and relative-Galois identifications.

Source context 5 commands

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

noncomputable section
namespace LocalClassFieldTheory
open LocalFieldTheory RamificationTheory CyclicCohomology KummerTheory
open ClassFormation LocalClassFieldTheory
variable (k Ω : Type) [Field k] [Field Ω] [Algebra k Ω] [IsGalois k Ω]
def abstractFixedFieldNormResidueSymbol
    (D : DegreeData (Gal(Ω/k)))
    (v : ValuationData D (galoisAmbientUnitsRep k Ω))
    (hcf : SatisfiesClassFieldAxiom
      (galoisAmbientUnitsRep k Ω))
    (K L : ClosedSubgroup (Gal(Ω/k)))
    (hLK : L.toSubgroup ≤ K.toSubgroup)
    [hnormal : (extensionSubgroup K L hLK).Normal]
    [hfinite : Finite
      (K.toSubgroup ⧸ extensionSubgroup K L hLK)]
    [hKabsolute : Finite
      ((baseField (Gal(Ω/k))).toSubgroup ⧸
        extensionSubgroup (baseField (Gal(Ω/k))) K
          (le_baseField K))] :
    Additive (abstractFixedField k Ω K)ˣ →+
      Additive (Abelianization
        Gal(abstractRelativeFixedField k Ω hLK /
          abstractFixedField k Ω K))
LocalClassFieldTheory.abstractFixedFieldNormUnits

The ordinary field norm on units between two concrete fixed fields.

Source context 5 commands

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

noncomputable section
namespace LocalClassFieldTheory
open LocalFieldTheory RamificationTheory CyclicCohomology KummerTheory
open ClassFormation LocalClassFieldTheory
variable (k Ω : Type) [Field k] [Field Ω] [Algebra k Ω] [IsGalois k Ω]
def abstractFixedFieldNormUnits
    (K K' : ClosedSubgroup (Gal(Ω/k)))
    (hK'K : K'.toSubgroup ≤ K.toSubgroup) :
    Additive (abstractRelativeFixedField k Ω hK'K)ˣ →+
      Additive (abstractFixedField k Ω K)ˣ
LocalClassFieldTheory.abstractFixedFieldAbelianizedRestriction

Restriction between the abelianized actual relative Galois groups in a fixed-field square, transported through the canonical quotient/Galois equivalences.

Source context 5 commands

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

noncomputable section
namespace LocalClassFieldTheory
open LocalFieldTheory RamificationTheory CyclicCohomology KummerTheory
open ClassFormation LocalClassFieldTheory
variable (k Ω : Type) [Field k] [Field Ω] [Algebra k Ω] [IsGalois k Ω]
def abstractFixedFieldAbelianizedRestriction
    (K K' L L' : ClosedSubgroup (Gal(Ω/k)))
    (hLK : L.toSubgroup ≤ K.toSubgroup)
    (hL'K' : L'.toSubgroup ≤ K'.toSubgroup)
    (hK'K : K'.toSubgroup ≤ K.toSubgroup)
    (hL'L : L'.toSubgroup ≤ L.toSubgroup)
    [hLnormal : (extensionSubgroup K L hLK).Normal]
    [hL'normal : (extensionSubgroup K' L' hL'K').Normal] :
    Additive (Abelianization
        Gal(abstractRelativeFixedField k Ω hL'K' /
          abstractFixedField k Ω K')) →+
      Additive (Abelianization
        Gal(abstractRelativeFixedField k Ω hLK /
          abstractFixedField k Ω K))
LocalClassFieldTheory.abstractFixedFieldAbelianizedRestriction_on_representative

On an ambient representative, the transported actual restriction is restriction of that same automorphism to the smaller upper fixed field.

Source context 5 commands

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

noncomputable section
namespace LocalClassFieldTheory
open LocalFieldTheory RamificationTheory CyclicCohomology KummerTheory
open ClassFormation LocalClassFieldTheory
variable (k Ω : Type) [Field k] [Field Ω] [Algebra k Ω] [IsGalois k Ω]
theorem abstractFixedFieldAbelianizedRestriction_on_representative
    (K K' L L' : ClosedSubgroup (Gal(Ω/k)))
    (hLK : L.toSubgroup ≤ K.toSubgroup)
    (hL'K' : L'.toSubgroup ≤ K'.toSubgroup)
    (hK'K : K'.toSubgroup ≤ K.toSubgroup)
    (hL'L : L'.toSubgroup ≤ L.toSubgroup)
    [hLnormal : (extensionSubgroup K L hLK).Normal]
    [hL'normal : (extensionSubgroup K' L' hL'K').Normal]
    (σ : K'.toSubgroup) :
    let q := abstractExtensionQuotientEquivGaloisGroup
      k Ω K L hLK hLnormal
    let q' := abstractExtensionQuotientEquivGaloisGroup
      k Ω K' L' hL'K' hL'normal
    abstractFixedFieldAbelianizedRestriction
        k Ω K K' L L' hLK hL'K' hK'K hL'L
        (Additive.ofMul
          (q'.abelianizationCongr
            (Abelianization.of (QuotientGroup.mk σ)))) =
      Additive.ofMul
        (q.abelianizationCongr
          (Abelianization.of
            (QuotientGroup.mk (Subgroup.inclusion hK'K σ)))) := by
  dsimp only
  let q := abstractExtensionQuotientEquivGaloisGroup
    k Ω K L hLK hLnormal
  let q' := abstractExtensionQuotientEquivGaloisGroup
    k Ω K' L' hL'K' hL'normal
  change Additive.ofMul
      (q.abelianizationCongr
        (normResidueNaturalityAbelianizedRestriction K K' L L'
          hLK hL'K' hK'K hL'L
          (q'.abelianizationCongr.symm
            (q'.abelianizationCongr
              (Abelianization.of (QuotientGroup.mk σ)))))) = _
  rw [q'.abelianizationCongr.symm_apply_apply]
  rw [normResidueNaturalityAbelianizedRestriction_of_mk]
LocalClassFieldTheory.abstractFixedFieldNormResidueSymbol_norm_restriction

Norm-restriction naturality for actual fixed fields. Actual Galois restriction is compatible with the ordinary unit norm and the unit-level norm-residue symbols. No normality of the intermediate extension K'/K is assumed.

Source context 5 commands

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

noncomputable section
namespace LocalClassFieldTheory
open LocalFieldTheory RamificationTheory CyclicCohomology KummerTheory
open ClassFormation LocalClassFieldTheory
variable (k Ω : Type) [Field k] [Field Ω] [Algebra k Ω] [IsGalois k Ω]
theorem abstractFixedFieldNormResidueSymbol_norm_restriction
    [IsSepClosed Ω]
    (D : DegreeData (Gal(Ω/k)))
    (v : ValuationData D (galoisAmbientUnitsRep k Ω))
    (hcf : SatisfiesClassFieldAxiom
      (galoisAmbientUnitsRep k Ω))
    (K K' L L' : ClosedSubgroup (Gal(Ω/k)))
    (hLK : L.toSubgroup ≤ K.toSubgroup)
    (hL'K' : L'.toSubgroup ≤ K'.toSubgroup)
    (hK'K : K'.toSubgroup ≤ K.toSubgroup)
    (hL'L : L'.toSubgroup ≤ L.toSubgroup)
    [hLnormal : (extensionSubgroup K L hLK).Normal]
    [hL'normal : (extensionSubgroup K' L' hL'K').Normal]
    [hLKfinite : Finite
      (K.toSubgroup ⧸ extensionSubgroup K L hLK)]
    [hL'K'finite : Finite
      (K'.toSubgroup ⧸ extensionSubgroup K' L' hL'K')]
    [hK'Kfinite : Finite
      (K.toSubgroup ⧸ extensionSubgroup K K' hK'K)]
    [hKabsolute : Finite
      ((baseField (Gal(Ω/k))).toSubgroup ⧸
        extensionSubgroup (baseField (Gal(Ω/k))) K
          (le_baseField K))] :
    letI : Finite ((baseField (Gal(Ω / k))).toSubgroup ⧸
        extensionSubgroup (baseField (Gal(Ω / k))) K'
          (le_baseField K')) :=
      relativeTowerQuotientFinite (baseField (Gal(Ω / k))) K K' hK'K
        (le_baseField K)
    (abstractFixedFieldAbelianizedRestriction
        k Ω K K' L L' hLK hL'K' hK'K hL'L).comp
      (abstractFixedFieldNormResidueSymbol
        k Ω D v hcf K' L' hL'K') =
      (abstractFixedFieldNormResidueSymbol
        k Ω D v hcf K L hLK).comp
        (abstractFixedFieldNormUnits k Ω K K' hK'K) := by
  let : Finite ((baseField (Gal(Ω / k))).toSubgroup ⧸
      extensionSubgroup (baseField (Gal(Ω / k))) K'
        (le_baseField K')) :=
    relativeTowerQuotientFinite (baseField (Gal(Ω / k))) K K' hK'K
      (le_baseField K)
  let KF : FiniteAbstractField (Gal(Ω / k)) :=
    ⟨K, hKabsolute⟩
  let K'F : FiniteAbstractField (Gal(Ω / k)) :=
    ⟨K', inferInstance⟩
  let T : FiniteAbstractFieldExtension (Gal(Ω / k)) :=
    { field := K'F
      base := KF
      below := hK'K
      finiteQuotient := hK'Kfinite }
  apply AddMonoidHom.ext
  intro x
  have h := DFunLike.congr_fun
    (D.normResidueNaturality_norm_restriction
      (galoisAmbientUnitsRep k Ω) v hcf
      T L L' hLK hL'K' hL'L)
    (finiteNormClass (galoisAmbientUnitsRep k Ω) K' L' hL'K'
      (abstractFixedFieldUnitsEquivGaloisFixed k Ω K' x))
  dsimp only [T, KF, K'F] at h
  let q := abstractExtensionQuotientEquivGaloisGroup
    k Ω K L hLK hLnormal
  let q' := abstractExtensionQuotientEquivGaloisGroup
    k Ω K' L' hL'K' hL'normal
  let E : FiniteGaloisSubextension KF.field :=
    ⟨L, hLK, hLnormal, hLKfinite⟩
  let E' : FiniteGaloisSubextension K'F.field :=
    ⟨L', hL'K', hL'normal, hL'K'finite⟩
  change Additive.ofMul
      (q.abelianizationCongr
        (normResidueNaturalityAbelianizedRestriction K K' L L'
          hLK hL'K' hK'K hL'L
          (q'.abelianizationCongr.symm
            (q'.abelianizationCongr
              (Additive.toMul
                (D.normResidueSymbol
                  (galoisAmbientUnitsRep k Ω) v hcf K'F E'
                  (finiteNormClass (galoisAmbientUnitsRep k Ω) K' L' hL'K'
                    (abstractFixedFieldUnitsEquivGaloisFixed
                      k Ω K' x)))))))) =
    Additive.ofMul
      (q.abelianizationCongr
        (Additive.toMul
          (D.normResidueSymbol
            (galoisAmbientUnitsRep k Ω) v hcf KF E
            (finiteNormClass (galoisAmbientUnitsRep k Ω) K L hLK
              (abstractFixedFieldUnitsEquivGaloisFixed k Ω K
                (abstractFixedFieldNormUnits
                  k Ω K K' hK'K x))))))
  apply Additive.toMul.injective
  change q.abelianizationCongr _ = q.abelianizationCongr _
  rw [q.abelianizationCongr.apply_eq_iff_eq]
  rw [q'.abelianizationCongr.symm_apply_apply]
  change _ =
    D.normResidueSymbol
      (galoisAmbientUnitsRep k Ω) v hcf KF E
        (finiteReciprocityNaturalityNormMap
          (galoisAmbientUnitsRep k Ω) K K' L L'
          hLK hL'K' hK'K hL'L
          (finiteNormClass (galoisAmbientUnitsRep k Ω) K' L' hL'K'
            (abstractFixedFieldUnitsEquivGaloisFixed k Ω K' x))) at h
  rw [finiteReciprocityNaturalityNormMap_finiteNormClass] at h
  have hxFixed :
      abstractFixedFieldUnitsEquivGaloisFixed k Ω K' x =
        abstractRelativeFixedFieldUnitsEquivGaloisFixed
          k Ω K K' hK'K
            (Additive.ofMul (Additive.toMul x)) := by
    rfl
  rw [hxFixed] at h
  rw [relativeNorm_abstractFixedFieldUnit_eq_normUnits
    k Ω K K' hK'K (Additive.toMul x)] at h
  exact congrArg Additive.toMul h
LocalClassFieldTheory.abstractFixedFieldAbelianizedTransfer

Transfer between the abelianized actual relative Galois groups in a fixed-field tower, transported through the two canonical quotient/Galois equivalences.

Source context 5 commands

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

noncomputable section
namespace LocalClassFieldTheory
open LocalFieldTheory RamificationTheory CyclicCohomology KummerTheory
open ClassFormation LocalClassFieldTheory
variable (k Ω : Type) [Field k] [Field Ω] [Algebra k Ω] [IsGalois k Ω]
def abstractFixedFieldAbelianizedTransfer
    (K K' L : ClosedSubgroup (Gal(Ω/k)))
    (hLK' : L.toSubgroup ≤ K'.toSubgroup)
    (hK'K : K'.toSubgroup ≤ K.toSubgroup)
    [hLnormal :
      (extensionSubgroup K L (hLK'.trans hK'K)).Normal]
    [hLfinite : Finite
      (K.toSubgroup ⧸
        extensionSubgroup K L (hLK'.trans hK'K))] :
    letI : (extensionSubgroup K' L hLK').Normal :=
      transferNormNaturality_intermediateExtension_normal K K' L hLK' hK'K
    letI : Finite
        (K'.toSubgroup ⧸ extensionSubgroup K' L hLK') :=
      FiniteGaloisSubextension.finite_extension_over_intermediate
        (hLK'.trans hK'K) hK'K hLK'
    Additive (Abelianization
        Gal(abstractRelativeFixedField k Ω (hLK'.trans hK'K) /
          abstractFixedField k Ω K)) →+
      Additive (Abelianization
        Gal(abstractRelativeFixedField k Ω hLK' /
          abstractFixedField k Ω K')) := by
  letI : (extensionSubgroup K' L hLK').Normal :=
    transferNormNaturality_intermediateExtension_normal K K' L hLK' hK'K
  letI : Finite
      (K'.toSubgroup ⧸ extensionSubgroup K' L hLK') :=
    FiniteGaloisSubextension.finite_extension_over_intermediate
      (hLK'.trans hK'K) hK'K hLK'
  exact MonoidHom.toAdditive
    ((abstractExtensionQuotientEquivGaloisGroup
      k Ω K' L hLK' inferInstance).abelianizationCongr.toMonoidHom.comp
      ((transferNormNaturalityTransfer K K' L hLK' hK'K).comp
        (abstractExtensionQuotientEquivGaloisGroup
          k Ω K L (hLK'.trans hK'K)
          hLnormal).abelianizationCongr.symm.toMonoidHom))
LocalClassFieldTheory.abstractFixedFieldNormResidueSymbol_transfer_inclusion

Transfer-inclusion naturality for actual fixed fields. Transfer of the actual relative Galois abelianizations is compatible with inclusion of actual fixed-field units and the unit-level norm-residue symbols.

Source context 5 commands

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

noncomputable section
namespace LocalClassFieldTheory
open LocalFieldTheory RamificationTheory CyclicCohomology KummerTheory
open ClassFormation LocalClassFieldTheory
variable (k Ω : Type) [Field k] [Field Ω] [Algebra k Ω] [IsGalois k Ω]
theorem abstractFixedFieldNormResidueSymbol_transfer_inclusion
    (D : DegreeData (Gal(Ω/k)))
    (v : ValuationData D (galoisAmbientUnitsRep k Ω))
    (hcf : SatisfiesClassFieldAxiom
      (galoisAmbientUnitsRep k Ω))
    (K K' L : ClosedSubgroup (Gal(Ω/k)))
    (hLK' : L.toSubgroup ≤ K'.toSubgroup)
    (hK'K : K'.toSubgroup ≤ K.toSubgroup)
    [hLnormal :
      (extensionSubgroup K L (hLK'.trans hK'K)).Normal]
    [hLfinite : Finite
      (K.toSubgroup ⧸
        extensionSubgroup K L (hLK'.trans hK'K))]
    [hKabsolute : Finite
      ((baseField (Gal(Ω/k))).toSubgroup ⧸
        extensionSubgroup (baseField (Gal(Ω/k))) K
          (le_baseField K))] :
    letI : (extensionSubgroup K' L hLK').Normal :=
      transferNormNaturality_intermediateExtension_normal K K' L hLK' hK'K
    letI : Finite
        (K'.toSubgroup ⧸ extensionSubgroup K' L hLK') :=
      FiniteGaloisSubextension.finite_extension_over_intermediate
        (hLK'.trans hK'K) hK'K hLK'
    letI : Finite
        (K.toSubgroup ⧸ extensionSubgroup K K' hK'K) :=
      FiniteGaloisSubextension.finite_intermediate_extension
        (hLK'.trans hK'K) hLK' hK'K
    letI : Finite ((baseField (Gal(Ω / k))).toSubgroup ⧸
        extensionSubgroup (baseField (Gal(Ω / k))) K'
          (le_baseField K')) :=
      relativeTowerQuotientFinite (baseField (Gal(Ω / k))) K K' hK'K
        (le_baseField K)
    (abstractFixedFieldAbelianizedTransfer
        k Ω K K' L hLK' hK'K).comp
      (abstractFixedFieldNormResidueSymbol
        k Ω D v hcf K L (hLK'.trans hK'K)) =
      (abstractFixedFieldNormResidueSymbol
        k Ω D v hcf K' L hLK').comp
        (abstractFixedFieldUnitsInclusion k Ω K K' hK'K) := by
  let : (extensionSubgroup K' L hLK').Normal :=
    transferNormNaturality_intermediateExtension_normal K K' L hLK' hK'K
  let : Finite
      (K'.toSubgroup ⧸ extensionSubgroup K' L hLK') :=
    FiniteGaloisSubextension.finite_extension_over_intermediate
      (hLK'.trans hK'K) hK'K hLK'
  let : Finite
      (K.toSubgroup ⧸ extensionSubgroup K K' hK'K) :=
    FiniteGaloisSubextension.finite_intermediate_extension
      (hLK'.trans hK'K) hLK' hK'K
  let : Finite ((baseField (Gal(Ω / k))).toSubgroup ⧸
      extensionSubgroup (baseField (Gal(Ω / k))) K'
        (le_baseField K')) :=
    relativeTowerQuotientFinite (baseField (Gal(Ω / k))) K K' hK'K
      (le_baseField K)
  let KF : FiniteAbstractField (Gal(Ω / k)) :=
    ⟨K, hKabsolute⟩
  let K'F : FiniteAbstractField (Gal(Ω / k)) :=
    ⟨K', inferInstance⟩
  let T : FiniteAbstractFieldExtension (Gal(Ω / k)) :=
    { field := K'F
      base := KF
      below := hK'K
      finiteQuotient := inferInstance }
  apply AddMonoidHom.ext
  intro x
  have h := DFunLike.congr_fun
    (D.normResidueNaturality_transfer_inclusion
      (galoisAmbientUnitsRep k Ω) v hcf
      T L hLK')
    (finiteNormClass (galoisAmbientUnitsRep k Ω)
      K L (hLK'.trans hK'K)
      (abstractFixedFieldUnitsEquivGaloisFixed k Ω K x))
  dsimp only [T, KF, K'F] at h
  let q := abstractExtensionQuotientEquivGaloisGroup
    k Ω K L (hLK'.trans hK'K) hLnormal
  let q' := abstractExtensionQuotientEquivGaloisGroup
    k Ω K' L hLK' (inferInstance :
      (extensionSubgroup K' L hLK').Normal)
  let E : FiniteGaloisSubextension KF.field :=
    ⟨L, hLK'.trans hK'K, hLnormal, hLfinite⟩
  let E' : FiniteGaloisSubextension K'F.field :=
    ⟨L, hLK', inferInstance, inferInstance⟩
  change Additive.ofMul
      (q'.abelianizationCongr
        (transferNormNaturalityTransfer K K' L hLK' hK'K
          (q.abelianizationCongr.symm
            (q.abelianizationCongr
              (Additive.toMul
                (D.normResidueSymbol
                  (galoisAmbientUnitsRep k Ω) v hcf KF E
                  (finiteNormClass (galoisAmbientUnitsRep k Ω)
                    K L (hLK'.trans hK'K)
                    (abstractFixedFieldUnitsEquivGaloisFixed
                      k Ω K x)))))))) =
    Additive.ofMul
      (q'.abelianizationCongr
        (Additive.toMul
          (D.normResidueSymbol
            (galoisAmbientUnitsRep k Ω) v hcf K'F E'
            (finiteNormClass (galoisAmbientUnitsRep k Ω) K' L hLK'
              (abstractFixedFieldUnitsEquivGaloisFixed k Ω K'
                (abstractFixedFieldUnitsInclusion
                  k Ω K K' hK'K x))))))
  apply Additive.toMul.injective
  change q'.abelianizationCongr _ = q'.abelianizationCongr _
  rw [q'.abelianizationCongr.apply_eq_iff_eq]
  rw [q.abelianizationCongr.symm_apply_apply]
  change _ =
    D.normResidueSymbol
      (galoisAmbientUnitsRep k Ω) v hcf K'F E'
        (transferNormNaturalityNormQuotientInclusion
          (galoisAmbientUnitsRep k Ω) K K' L hLK' hK'K
          (finiteNormClass (galoisAmbientUnitsRep k Ω)
            K L (hLK'.trans hK'K)
            (abstractFixedFieldUnitsEquivGaloisFixed k Ω K x))) at h
  rw [transferNormNaturality_normQuotientInclusion_finiteNormClass] at h
  rw [← abstractFixedFieldUnitsEquiv_inclusion k Ω K K' hK'K x] at h
  exact congrArg Additive.toMul h
LocalClassFieldTheory.LocalFixedFieldNormRestrictionSquare

A finite fixed-field square encoding norm-restriction naturality inside the separable closure of a local field.

The two horizontal extensions are finite Galois. The vertical base extension is finite but need not be normal.

Source context 6 commands

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

noncomputable section
namespace LocalClassFieldTheory
open LocalFieldTheory RamificationTheory CyclicCohomology KummerTheory
open ClassFormation LocalClassFieldTheory
variable (k Ω : Type) [Field k] [Field Ω] [Algebra k Ω] [IsGalois k Ω]
open scoped ValuativeRel
structure LocalFixedFieldNormRestrictionSquare
    (k : Type) [Field k] [ValuativeRel k] [TopologicalSpace k]
    [IsNonarchimedeanLocalField k] where
  /-- The subgroup fixing the lower base field. -/
  lowerBase : ClosedSubgroup (Gal(SeparableClosure k / k))
  /-- The subgroup fixing the upper base field. -/
  upperBase : ClosedSubgroup (Gal(SeparableClosure k / k))
  /-- The subgroup fixing the top field of the lower horizontal extension. -/
  lowerTop : ClosedSubgroup (Gal(SeparableClosure k / k))
  /-- The subgroup fixing the top field of the upper horizontal extension. -/
  upperTop : ClosedSubgroup (Gal(SeparableClosure k / k))
  /-- The lower top subgroup lies in the lower base subgroup. -/
  lowerTop_le_lowerBase : lowerTop.toSubgroup ≤ lowerBase.toSubgroup
  /-- The upper top subgroup lies in the upper base subgroup. -/
  upperTop_le_upperBase : upperTop.toSubgroup ≤ upperBase.toSubgroup
  /-- The upper base subgroup lies in the lower base subgroup. -/
  upperBase_le_lowerBase : upperBase.toSubgroup ≤ lowerBase.toSubgroup
  /-- The upper top subgroup lies in the lower top subgroup. -/
  upperTop_le_lowerTop : upperTop.toSubgroup ≤ lowerTop.toSubgroup
  /-- The lower horizontal extension subgroup is normal. -/
  lowerNormal :
    (extensionSubgroup lowerBase lowerTop lowerTop_le_lowerBase).Normal
  /-- The upper horizontal extension subgroup is normal. -/
  upperNormal :
    (extensionSubgroup upperBase upperTop upperTop_le_upperBase).Normal
  /-- The lower horizontal extension has finite Galois group. -/
  lowerFinite :
    Finite (lowerBase.toSubgroup ⧸
      extensionSubgroup lowerBase lowerTop lowerTop_le_lowerBase)
  /-- The upper horizontal extension has finite Galois group. -/
  upperFinite :
    Finite (upperBase.toSubgroup ⧸
      extensionSubgroup upperBase upperTop upperTop_le_upperBase)
  /-- The vertical base extension has finite degree. -/
  baseFinite :
    Finite (lowerBase.toSubgroup ⧸
      extensionSubgroup lowerBase upperBase upperBase_le_lowerBase)
  /-- The lower base field is finite over the original local field. -/
  lowerAbsoluteFinite :
    Finite
      ((baseField (Gal(SeparableClosure k / k))).toSubgroup ⧸
        extensionSubgroup (baseField (Gal(SeparableClosure k / k)))
          lowerBase (le_baseField lowerBase))
LocalClassFieldTheory.LocalFixedFieldNormRestrictionSquare.upperAbsoluteFinite

The quotient from the absolute subgroup to the upper fixed-field subgroup is finite.

Source context 8 commands

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

noncomputable section
namespace LocalClassFieldTheory
open LocalFieldTheory RamificationTheory CyclicCohomology KummerTheory
open ClassFormation LocalClassFieldTheory
variable (k Ω : Type) [Field k] [Field Ω] [Algebra k Ω] [IsGalois k Ω]
open scoped ValuativeRel
namespace LocalFixedFieldNormRestrictionSquare
variable {k : Type} [Field k] [ValuativeRel k] [TopologicalSpace k]
  [IsNonarchimedeanLocalField k]
theorem upperAbsoluteFinite
    (T : LocalFixedFieldNormRestrictionSquare k) :
    Finite
      ((baseField (Gal(SeparableClosure k / k))).toSubgroup ⧸
        extensionSubgroup (baseField (Gal(SeparableClosure k / k)))
          T.upperBase (le_baseField T.upperBase))
LocalClassFieldTheory.LocalFixedFieldNormRestrictionSquare.lowerNormResidueSymbol

The fixed-field norm-residue symbol for the lower horizontal extension, induced by the canonical local class formation.

Source context 8 commands

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

noncomputable section
namespace LocalClassFieldTheory
open LocalFieldTheory RamificationTheory CyclicCohomology KummerTheory
open ClassFormation LocalClassFieldTheory
variable (k Ω : Type) [Field k] [Field Ω] [Algebra k Ω] [IsGalois k Ω]
open scoped ValuativeRel
namespace LocalFixedFieldNormRestrictionSquare
variable {k : Type} [Field k] [ValuativeRel k] [TopologicalSpace k]
  [IsNonarchimedeanLocalField k]
def lowerNormResidueSymbol
    (T : LocalFixedFieldNormRestrictionSquare k)
LocalClassFieldTheory.LocalFixedFieldNormRestrictionSquare.upperNormResidueSymbol

The fixed-field norm-residue symbol for the upper horizontal extension, induced by the canonical local class formation.

Source context 8 commands

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

noncomputable section
namespace LocalClassFieldTheory
open LocalFieldTheory RamificationTheory CyclicCohomology KummerTheory
open ClassFormation LocalClassFieldTheory
variable (k Ω : Type) [Field k] [Field Ω] [Algebra k Ω] [IsGalois k Ω]
open scoped ValuativeRel
namespace LocalFixedFieldNormRestrictionSquare
variable {k : Type} [Field k] [ValuativeRel k] [TopologicalSpace k]
  [IsNonarchimedeanLocalField k]
def upperNormResidueSymbol
    (T : LocalFixedFieldNormRestrictionSquare k)
LocalClassFieldTheory.LocalFixedFieldNormRestrictionSquare.normUnits

The ordinary field norm on units along the vertical base extension.

Source context 8 commands

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

noncomputable section
namespace LocalClassFieldTheory
open LocalFieldTheory RamificationTheory CyclicCohomology KummerTheory
open ClassFormation LocalClassFieldTheory
variable (k Ω : Type) [Field k] [Field Ω] [Algebra k Ω] [IsGalois k Ω]
open scoped ValuativeRel
namespace LocalFixedFieldNormRestrictionSquare
variable {k : Type} [Field k] [ValuativeRel k] [TopologicalSpace k]
  [IsNonarchimedeanLocalField k]
def normUnits
    (T : LocalFixedFieldNormRestrictionSquare k)
LocalClassFieldTheory.LocalFixedFieldNormRestrictionSquare.abelianizedRestriction

Restriction between the abelianized actual relative Galois groups.

Source context 8 commands

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

noncomputable section
namespace LocalClassFieldTheory
open LocalFieldTheory RamificationTheory CyclicCohomology KummerTheory
open ClassFormation LocalClassFieldTheory
variable (k Ω : Type) [Field k] [Field Ω] [Algebra k Ω] [IsGalois k Ω]
open scoped ValuativeRel
namespace LocalFixedFieldNormRestrictionSquare
variable {k : Type} [Field k] [ValuativeRel k] [TopologicalSpace k]
  [IsNonarchimedeanLocalField k]
def abelianizedRestriction
    (T : LocalFixedFieldNormRestrictionSquare k)
LocalClassFieldTheory.LocalFixedFieldNormRestrictionSquare.norm_restriction_commutes

Canonical norm-restriction naturality for a local fixed-field square. Restriction commutes with the ordinary field norm and the fixed-field norm-residue symbols induced by the canonical local class formation for the finite Galois square bundled by T; no normality of the vertical base extension is required.

Source context 8 commands

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

noncomputable section
namespace LocalClassFieldTheory
open LocalFieldTheory RamificationTheory CyclicCohomology KummerTheory
open ClassFormation LocalClassFieldTheory
variable (k Ω : Type) [Field k] [Field Ω] [Algebra k Ω] [IsGalois k Ω]
open scoped ValuativeRel
namespace LocalFixedFieldNormRestrictionSquare
variable {k : Type} [Field k] [ValuativeRel k] [TopologicalSpace k]
  [IsNonarchimedeanLocalField k]
theorem norm_restriction_commutes
    (T : LocalFixedFieldNormRestrictionSquare k) :
    (abelianizedRestriction T).comp (upperNormResidueSymbol T) =
      (lowerNormResidueSymbol T).comp (normUnits T)
LocalClassFieldTheory.LocalFixedFieldTransferTower

A finite fixed-field tower encoding transfer-inclusion naturality inside the separable closure of a local field.

The total extension is finite Galois. Normality and finiteness of the upper part of the tower are derived internally.

Source context 6 commands

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

noncomputable section
namespace LocalClassFieldTheory
open LocalFieldTheory RamificationTheory CyclicCohomology KummerTheory
open ClassFormation LocalClassFieldTheory
variable (k Ω : Type) [Field k] [Field Ω] [Algebra k Ω] [IsGalois k Ω]
open scoped ValuativeRel
structure LocalFixedFieldTransferTower
    (k : Type) [Field k] [ValuativeRel k] [TopologicalSpace k]
    [IsNonarchimedeanLocalField k] where
  /-- The subgroup fixing the base field of the tower. -/
  base : ClosedSubgroup (Gal(SeparableClosure k / k))
  /-- The subgroup fixing the intermediate field of the tower. -/
  intermediate : ClosedSubgroup (Gal(SeparableClosure k / k))
  /-- The subgroup fixing the top field of the tower. -/
  top : ClosedSubgroup (Gal(SeparableClosure k / k))
  /-- The top subgroup lies in the intermediate subgroup. -/
  top_le_intermediate : top.toSubgroup ≤ intermediate.toSubgroup
  /-- The intermediate subgroup lies in the base subgroup. -/
  intermediate_le_base : intermediate.toSubgroup ≤ base.toSubgroup
  /-- The total extension subgroup is normal in the base subgroup. -/
  totalNormal :
    (extensionSubgroup base top
      (top_le_intermediate.trans intermediate_le_base)).Normal
  /-- The total extension has finite Galois group. -/
  totalFinite :
    Finite (base.toSubgroup ⧸
      extensionSubgroup base top
        (top_le_intermediate.trans intermediate_le_base))
  /-- The base field is finite over the original local field. -/
  baseAbsoluteFinite :
    Finite
      ((baseField (Gal(SeparableClosure k / k))).toSubgroup ⧸
        extensionSubgroup (baseField (Gal(SeparableClosure k / k)))
          base (le_baseField base))
LocalClassFieldTheory.LocalFixedFieldTransferTower.intermediateNormal

The top extension subgroup is normal inside the intermediate subgroup.

Source context 8 commands

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

noncomputable section
namespace LocalClassFieldTheory
open LocalFieldTheory RamificationTheory CyclicCohomology KummerTheory
open ClassFormation LocalClassFieldTheory
variable (k Ω : Type) [Field k] [Field Ω] [Algebra k Ω] [IsGalois k Ω]
open scoped ValuativeRel
namespace LocalFixedFieldTransferTower
variable {k : Type} [Field k] [ValuativeRel k] [TopologicalSpace k]
  [IsNonarchimedeanLocalField k]
theorem intermediateNormal (T : LocalFixedFieldTransferTower k) :
    (extensionSubgroup T.intermediate T.top
      T.top_le_intermediate).Normal
LocalClassFieldTheory.LocalFixedFieldTransferTower.intermediateFinite

The quotient of the intermediate subgroup by the top extension subgroup is finite.

Source context 8 commands

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

noncomputable section
namespace LocalClassFieldTheory
open LocalFieldTheory RamificationTheory CyclicCohomology KummerTheory
open ClassFormation LocalClassFieldTheory
variable (k Ω : Type) [Field k] [Field Ω] [Algebra k Ω] [IsGalois k Ω]
open scoped ValuativeRel
namespace LocalFixedFieldTransferTower
variable {k : Type} [Field k] [ValuativeRel k] [TopologicalSpace k]
  [IsNonarchimedeanLocalField k]
theorem intermediateFinite (T : LocalFixedFieldTransferTower k) :
    Finite (T.intermediate.toSubgroup ⧸
      extensionSubgroup T.intermediate T.top
        T.top_le_intermediate)
LocalClassFieldTheory.LocalFixedFieldTransferTower.baseIntermediateFinite

The quotient of the base subgroup by the intermediate extension subgroup is finite.

Source context 8 commands

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

noncomputable section
namespace LocalClassFieldTheory
open LocalFieldTheory RamificationTheory CyclicCohomology KummerTheory
open ClassFormation LocalClassFieldTheory
variable (k Ω : Type) [Field k] [Field Ω] [Algebra k Ω] [IsGalois k Ω]
open scoped ValuativeRel
namespace LocalFixedFieldTransferTower
variable {k : Type} [Field k] [ValuativeRel k] [TopologicalSpace k]
  [IsNonarchimedeanLocalField k]
theorem baseIntermediateFinite
    (T : LocalFixedFieldTransferTower k) :
    Finite (T.base.toSubgroup ⧸
      extensionSubgroup T.base T.intermediate
        T.intermediate_le_base)
LocalClassFieldTheory.LocalFixedFieldTransferTower.intermediateAbsoluteFinite

The absolute quotient determined by the intermediate fixed field is finite.

Source context 8 commands

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

noncomputable section
namespace LocalClassFieldTheory
open LocalFieldTheory RamificationTheory CyclicCohomology KummerTheory
open ClassFormation LocalClassFieldTheory
variable (k Ω : Type) [Field k] [Field Ω] [Algebra k Ω] [IsGalois k Ω]
open scoped ValuativeRel
namespace LocalFixedFieldTransferTower
variable {k : Type} [Field k] [ValuativeRel k] [TopologicalSpace k]
  [IsNonarchimedeanLocalField k]
theorem intermediateAbsoluteFinite
    (T : LocalFixedFieldTransferTower k) :
    Finite
      ((baseField (Gal(SeparableClosure k / k))).toSubgroup ⧸
        extensionSubgroup (baseField (Gal(SeparableClosure k / k)))
          T.intermediate (le_baseField T.intermediate))
LocalClassFieldTheory.LocalFixedFieldTransferTower.baseNormResidueSymbol

The fixed-field norm-residue symbol for the total extension, induced by the canonical local class formation.

Source context 8 commands

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

noncomputable section
namespace LocalClassFieldTheory
open LocalFieldTheory RamificationTheory CyclicCohomology KummerTheory
open ClassFormation LocalClassFieldTheory
variable (k Ω : Type) [Field k] [Field Ω] [Algebra k Ω] [IsGalois k Ω]
open scoped ValuativeRel
namespace LocalFixedFieldTransferTower
variable {k : Type} [Field k] [ValuativeRel k] [TopologicalSpace k]
  [IsNonarchimedeanLocalField k]
def baseNormResidueSymbol
    (T : LocalFixedFieldTransferTower k)
LocalClassFieldTheory.LocalFixedFieldTransferTower.intermediateNormResidueSymbol

The fixed-field norm-residue symbol after changing the base to the intermediate fixed field, induced by the canonical local class formation.

Source context 8 commands

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

noncomputable section
namespace LocalClassFieldTheory
open LocalFieldTheory RamificationTheory CyclicCohomology KummerTheory
open ClassFormation LocalClassFieldTheory
variable (k Ω : Type) [Field k] [Field Ω] [Algebra k Ω] [IsGalois k Ω]
open scoped ValuativeRel
namespace LocalFixedFieldTransferTower
variable {k : Type} [Field k] [ValuativeRel k] [TopologicalSpace k]
  [IsNonarchimedeanLocalField k]
def intermediateNormResidueSymbol
    (T : LocalFixedFieldTransferTower k)
LocalClassFieldTheory.LocalFixedFieldTransferTower.unitsInclusion

Inclusion of actual fixed-field units along the base change.

Source context 8 commands

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

noncomputable section
namespace LocalClassFieldTheory
open LocalFieldTheory RamificationTheory CyclicCohomology KummerTheory
open ClassFormation LocalClassFieldTheory
variable (k Ω : Type) [Field k] [Field Ω] [Algebra k Ω] [IsGalois k Ω]
open scoped ValuativeRel
namespace LocalFixedFieldTransferTower
variable {k : Type} [Field k] [ValuativeRel k] [TopologicalSpace k]
  [IsNonarchimedeanLocalField k]
def unitsInclusion
    (T : LocalFixedFieldTransferTower k)
LocalClassFieldTheory.LocalFixedFieldTransferTower.abelianizedTransfer

Transfer between the abelianized actual relative Galois groups.

Source context 8 commands

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

noncomputable section
namespace LocalClassFieldTheory
open LocalFieldTheory RamificationTheory CyclicCohomology KummerTheory
open ClassFormation LocalClassFieldTheory
variable (k Ω : Type) [Field k] [Field Ω] [Algebra k Ω] [IsGalois k Ω]
open scoped ValuativeRel
namespace LocalFixedFieldTransferTower
variable {k : Type} [Field k] [ValuativeRel k] [TopologicalSpace k]
  [IsNonarchimedeanLocalField k]
def abelianizedTransfer
    (T : LocalFixedFieldTransferTower k)
LocalClassFieldTheory.LocalFixedFieldTransferTower.transfer_inclusion_commutes

Canonical transfer-inclusion naturality for a local fixed-field tower. Transfer commutes with inclusion of fixed-field units and the fixed-field norm-residue symbols induced by the canonical local class formation for the finite Galois tower bundled by T.

Source context 8 commands

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

noncomputable section
namespace LocalClassFieldTheory
open LocalFieldTheory RamificationTheory CyclicCohomology KummerTheory
open ClassFormation LocalClassFieldTheory
variable (k Ω : Type) [Field k] [Field Ω] [Algebra k Ω] [IsGalois k Ω]
open scoped ValuativeRel
namespace LocalFixedFieldTransferTower
variable {k : Type} [Field k] [ValuativeRel k] [TopologicalSpace k]
  [IsNonarchimedeanLocalField k]
theorem transfer_inclusion_commutes
    (T : LocalFixedFieldTransferTower k) :
    (abelianizedTransfer T).comp (baseNormResidueSymbol T) =
      (intermediateNormResidueSymbol T).comp (unitsInclusion T)