Module

Reassociation.lean

Nyll.ClassFieldTheory.AlgebraicNumberTheory.Idele.Cohomology.SPlaces.Reassociation
9 declarations indexed from sourceView source ↗

Reassociation of supported relative-idele factors

The factor model of a supported relative idele is reassociated into the finite family of unrestricted places and the product of integral factors outside the support. The comparison respects the concrete Galois actions.

Declarations

The product of the actual integral tensor-unit factors outside S.

Source context 6 commands

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

open scoped NumberField
open NumberField IsDedekindDomain
noncomputable section
open CyclicCohomology.ProfiniteCohomology.Herbrand
open CyclicCohomology
variable
    {K L : Type}
    [Field K] [NumberField K]
    [Field L] [NumberField L] [Algebra K L]
    [FiniteDimensional K L] [IsGalois K L]
abbrev RelativeOutsideSPlaceFactors
    (S : Finset (HeightOneSpectrum (𝓞 K)))

The componentwise Galois action on the integral factors outside S.

Source context 6 commands

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

open scoped NumberField
open NumberField IsDedekindDomain
noncomputable section
open CyclicCohomology.ProfiniteCohomology.Herbrand
open CyclicCohomology
variable
    {K L : Type}
    [Field K] [NumberField K]
    [Field L] [NumberField L] [Algebra K L]
    [FiniteDimensional K L] [IsGalois K L]
def relativeOutsideSPlaceFactorsAction
    (S : Finset (HeightOneSpectrum (𝓞 K))) :
    MulDistribMulAction (L ≃ₐ[K] L)
      (RelativeOutsideSPlaceFactors
        (K := K) (L := L) S)

The componentwise Galois action on the product of unrestricted and outside-integral local factors.

Source context 6 commands

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

open scoped NumberField
open NumberField IsDedekindDomain
noncomputable section
open CyclicCohomology.ProfiniteCohomology.Herbrand
open CyclicCohomology
variable
    {K L : Type}
    [Field K] [NumberField K]
    [Field L] [NumberField L] [Algebra K L]
    [FiniteDimensional K L] [IsGalois K L]
def relativeUnrestrictedProdOutsideAction
    (S : Finset (HeightOneSpectrum (𝓞 K))) :
    MulDistribMulAction (L ≃ₐ[K] L)
      (RelativeUnrestrictedSPlaceFactors
          (K := K) (L := L) S ×
        RelativeOutsideSPlaceFactors
          (K := K) (L := L) S)

Reassociate all supported local factors as (unrestricted factors) × (outside integral factors).

Source context 6 commands

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

open scoped NumberField
open NumberField IsDedekindDomain
noncomputable section
open CyclicCohomology.ProfiniteCohomology.Herbrand
open CyclicCohomology
variable
    {K L : Type}
    [Field K] [NumberField K]
    [Field L] [NumberField L] [Algebra K L]
    [FiniteDimensional K L] [IsGalois K L]
def
    relativeIdeleSPlaceFactorsEquivUnrestrictedProdOutside
    (S : Finset (HeightOneSpectrum (𝓞 K))) :
    RelativeIdeleSPlaceFactors (K := K) (L := L) S ≃*
      RelativeUnrestrictedSPlaceFactors
          (K := K) (L := L) S ×
        RelativeOutsideSPlaceFactors
          (K := K) (L := L) S where
  toFun z :=
    ⟨fun i =>
      match i with
      | Sum.inl w => z.1 w
      | Sum.inr w => z.2.1 w,
      z.2.2⟩
  invFun z :=
    ⟨fun w => z.1 (Sum.inl w),
      ⟨fun w => z.1 (Sum.inr w), z.2⟩⟩
  left_inv _ := rfl
  right_inv z := by
    apply Prod.ext
    · funext i
      cases i <;> rfl
    · rfl
  map_mul' x y := by
    apply Prod.ext
    · funext i
      cases i <;> rfl
    · rfl

The reassociation of supported local factors is Galois equivariant.

Source context 7 commands

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

open scoped NumberField
open NumberField IsDedekindDomain
noncomputable section
open CyclicCohomology.ProfiniteCohomology.Herbrand
open CyclicCohomology
variable
    {K L : Type}
    [Field K] [NumberField K]
    [Field L] [NumberField L] [Algebra K L]
    [FiniteDimensional K L] [IsGalois K L]
omit [NumberField L] [IsGalois K L] in
theorem
    relativeIdeleSPlaceFactorsEquivUnrestrictedProdOutside_smul
    (S : Finset (HeightOneSpectrum (𝓞 K)))
    (σ : L ≃ₐ[K] L)
    (z : RelativeIdeleSPlaceFactors
      (K := K) (L := L) S) :
    relativeIdeleSPlaceFactorsEquivUnrestrictedProdOutside
        (K := K) (L := L) S
        ((relativeIdeleSPlaceFactorsAction
          (K := K) (L := L) S).smul σ z) =
      (relativeUnrestrictedProdOutsideAction
        (K := K) (L := L) S).smul σ
        (relativeIdeleSPlaceFactorsEquivUnrestrictedProdOutside
          (K := K) (L := L) S z)

The complete supported relative-idele group, with its restricted-product condition already built into the subtype, is the product of the unrestricted local factors in S and the integral local factors outside S.

Source context 6 commands

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

open scoped NumberField
open NumberField IsDedekindDomain
noncomputable section
open CyclicCohomology.ProfiniteCohomology.Herbrand
open CyclicCohomology
variable
    {K L : Type}
    [Field K] [NumberField K]
    [Field L] [NumberField L] [Algebra K L]
    [FiniteDimensional K L] [IsGalois K L]
def
    relativeIdeleSupportedEquivUnrestrictedProdOutside
    (S : Finset (HeightOneSpectrum (𝓞 K))) :
    relativeIdeleLocalTensorDecompositionSupportedSubgroup
          (K := K) (L := L) S ≃*
      RelativeUnrestrictedSPlaceFactors
          (K := K) (L := L) S ×
        RelativeOutsideSPlaceFactors
          (K := K) (L := L) S

The supported relative-idele decomposition is equivariant for the concrete Galois action on every factor.

Source context 7 commands

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

open scoped NumberField
open NumberField IsDedekindDomain
noncomputable section
open CyclicCohomology.ProfiniteCohomology.Herbrand
open CyclicCohomology
variable
    {K L : Type}
    [Field K] [NumberField K]
    [Field L] [NumberField L] [Algebra K L]
    [FiniteDimensional K L] [IsGalois K L]
omit [IsGalois K L] in
theorem
    relativeIdeleSupportedEquivUnrestrictedProdOutside_smul
    (S : Finset (HeightOneSpectrum (𝓞 K)))
    (σ : L ≃ₐ[K] L)
    (z : relativeIdeleLocalTensorDecompositionSupportedSubgroup
      (K := K) (L := L) S) :
    relativeIdeleSupportedEquivUnrestrictedProdOutside
        (K := K) (L := L) S
        ((relativeIdeleLocalTensorDecompositionSupportedSubgroupAction
          (K := K) (L := L) S).smul σ z) =
      (relativeUnrestrictedProdOutsideAction
        (K := K) (L := L) S).smul σ
        (relativeIdeleSupportedEquivUnrestrictedProdOutside
          (K := K) (L := L) S z)

Transport of degree-zero Tate cohomology from the actual supported relative ideles to the unrestricted and outside-integral factorization.

Source context 6 commands

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

open scoped NumberField
open NumberField IsDedekindDomain
noncomputable section
open CyclicCohomology.ProfiniteCohomology.Herbrand
open CyclicCohomology
variable
    {K L : Type}
    [Field K] [NumberField K]
    [Field L] [NumberField L] [Algebra K L]
    [FiniteDimensional K L] [IsGalois K L]
def
    relativeIdeleSupportedHerbrandH0EquivUnrestrictedProdOutside
    (S : Finset (HeightOneSpectrum (𝓞 K))) :
    letI :=
      relativeIdeleLocalTensorDecompositionSupportedSubgroupAction
        (K := K) (L := L) S
    letI :=
      relativeUnrestrictedProdOutsideAction
        (K := K) (L := L) S
    HerbrandH0 (L ≃ₐ[K] L)
        (relativeIdeleLocalTensorDecompositionSupportedSubgroup
          (K := K) (L := L) S) ≃*
      HerbrandH0 (L ≃ₐ[K] L)
        (RelativeUnrestrictedSPlaceFactors
            (K := K) (L := L) S ×
          RelativeOutsideSPlaceFactors
            (K := K) (L := L) S) := by
  letI :=
    relativeIdeleLocalTensorDecompositionSupportedSubgroupAction
      (K := K) (L := L) S
  letI :=
    relativeUnrestrictedProdOutsideAction
      (K := K) (L := L) S
  exact
    herbrandH0EquivariantMulEquiv
      (relativeIdeleSupportedEquivUnrestrictedProdOutside
        (K := K) (L := L) S)
      (relativeIdeleSupportedEquivUnrestrictedProdOutside_smul
        (K := K) (L := L) S)

Transport of degree-minus-one Tate cohomology from the actual supported relative ideles to the unrestricted and outside-integral factorization.

Source context 6 commands

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

open scoped NumberField
open NumberField IsDedekindDomain
noncomputable section
open CyclicCohomology.ProfiniteCohomology.Herbrand
open CyclicCohomology
variable
    {K L : Type}
    [Field K] [NumberField K]
    [Field L] [NumberField L] [Algebra K L]
    [FiniteDimensional K L] [IsGalois K L]
def
    relativeIdeleSupportedHerbrandHMinusOneEquivUnrestrictedProdOutside
    (S : Finset (HeightOneSpectrum (𝓞 K)))
    (σ : L ≃ₐ[K] L) :
    letI :=
      relativeIdeleLocalTensorDecompositionSupportedSubgroupAction
        (K := K) (L := L) S
    letI :=
      relativeUnrestrictedProdOutsideAction
        (K := K) (L := L) S
    HerbrandHMinusOne (L ≃ₐ[K] L)
        (relativeIdeleLocalTensorDecompositionSupportedSubgroup
          (K := K) (L := L) S) σ ≃*
      HerbrandHMinusOne (L ≃ₐ[K] L)
        (RelativeUnrestrictedSPlaceFactors
            (K := K) (L := L) S ×
          RelativeOutsideSPlaceFactors
            (K := K) (L := L) S) σ := by
  letI :=
    relativeIdeleLocalTensorDecompositionSupportedSubgroupAction
      (K := K) (L := L) S
  letI :=
    relativeUnrestrictedProdOutsideAction
      (K := K) (L := L) S
  exact
    herbrandHMinusOneEquivariantMulEquiv
      (relativeIdeleSupportedEquivUnrestrictedProdOutside
        (K := K) (L := L) S)
      (relativeIdeleSupportedEquivUnrestrictedProdOutside_smul
        (K := K) (L := L) S) σ