Module

Support.lean

Nyll.ClassFieldTheory.AlgebraicNumberTheory.Idele.Relative.Support
25 declarations indexed from sourceView source β†—

Finite coefficient support for relative ideles

This file supplies the finite-support input for the actual scalar-extension model

𝔸_K βŠ—[K] L.

Fixing the canonical chosen K-basis of L, every relative adele has finitely many base-adele coefficients. For a relative idele we take the union of the nonintegral finite places of the coefficients of the idele and of its inverse. Outside this finite set both local tensor components therefore lie in the lattice spanned by that basis over the local valuation ring.

This produces the finite support from a basis lattice. Passing from that lattice to the product of local integer rings additionally requires integral compatibility of the relative tensor decomposition.

Declarations

The finite index type of the canonical chosen K-basis of L.

Source context 5 commands

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

open scoped NumberField TensorProduct
open NumberField IsDedekindDomain
noncomputable section
universe u v
variable
    {K : Type u} {L : Type v}
    [Field K] [NumberField K]
    [Field L] [NumberField L] [Algebra K L]
    [FiniteDimensional K L]
abbrev RelativeAdeleBasisIndex

The canonical chosen K-basis used to extract base-adele coefficients.

Source context 5 commands

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

open scoped NumberField TensorProduct
open NumberField IsDedekindDomain
noncomputable section
universe u v
variable
    {K : Type u} {L : Type v}
    [Field K] [NumberField K]
    [Field L] [NumberField L] [Algebra K L]
    [FiniteDimensional K L]
def relativeExtensionBasis :
    Module.Basis (RelativeAdeleBasisIndex (K := K) (L := L)) K L

Scalar extension of the chosen basis from K to 𝔸_K.

Source context 5 commands

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

open scoped NumberField TensorProduct
open NumberField IsDedekindDomain
noncomputable section
universe u v
variable
    {K : Type u} {L : Type v}
    [Field K] [NumberField K]
    [Field L] [NumberField L] [Algebra K L]
    [FiniteDimensional K L]
def relativeAdeleBasis :
    Module.Basis (RelativeAdeleBasisIndex (K := K) (L := L))
      (NumberField.AdeleRing (π“ž K) K)
      (RelativeAdeleRing K L)

The i-th base-adele coefficient of a relative adele.

Source context 5 commands

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

open scoped NumberField TensorProduct
open NumberField IsDedekindDomain
noncomputable section
universe u v
variable
    {K : Type u} {L : Type v}
    [Field K] [NumberField K]
    [Field L] [NumberField L] [Algebra K L]
    [FiniteDimensional K L]
def relativeAdeleCoefficient
    (z : RelativeAdeleRing K L)
    (i : RelativeAdeleBasisIndex (K := K) (L := L)) :
    NumberField.AdeleRing (π“ž K) K

Expansion of a relative adele in the chosen extension basis.

Source context 6 commands

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

open scoped NumberField TensorProduct
open NumberField IsDedekindDomain
noncomputable section
universe u v
variable
    {K : Type u} {L : Type v}
    [Field K] [NumberField K]
    [Field L] [NumberField L] [Algebra K L]
    [FiniteDimensional K L]
omit [NumberField L] in
theorem relativeAdele_eq_sum_tmul_coefficients
    (z : RelativeAdeleRing K L) :
    z =
      βˆ‘ i : RelativeAdeleBasisIndex (K := K) (L := L),
        relativeAdeleCoefficient
            (K := K) (L := L) z i βŠ—β‚œ[K]
          relativeExtensionBasis (K := K) (L := L) i

Evaluation at a finite place is coefficientwise in the chosen basis expansion.

Source context 6 commands

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

open scoped NumberField TensorProduct
open NumberField IsDedekindDomain
noncomputable section
universe u v
variable
    {K : Type u} {L : Type v}
    [Field K] [NumberField K]
    [Field L] [NumberField L] [Algebra K L]
    [FiniteDimensional K L]
omit [NumberField L] in
theorem relativeAdeleFiniteComponent_eq_sum_tmul_coefficients
    (z : RelativeAdeleRing K L)
    (w : HeightOneSpectrum (π“ž K)) :
    relativeAdeleFiniteComponent
        (K := K) (L := L) w z =
      βˆ‘ i : RelativeAdeleBasisIndex (K := K) (L := L),
        (relativeAdeleCoefficient
            (K := K) (L := L) z i).2 w βŠ—β‚œ[K]
          relativeExtensionBasis (K := K) (L := L) i

Evaluation at an infinite place is coefficientwise in the chosen basis expansion.

Source context 6 commands

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

open scoped NumberField TensorProduct
open NumberField IsDedekindDomain
noncomputable section
universe u v
variable
    {K : Type u} {L : Type v}
    [Field K] [NumberField K]
    [Field L] [NumberField L] [Algebra K L]
    [FiniteDimensional K L]
omit [NumberField L] in
theorem relativeAdeleInfiniteComponent_eq_sum_tmul_coefficients
    (z : RelativeAdeleRing K L)
    (w : InfinitePlace K) :
    relativeAdeleInfiniteComponent
        (K := K) (L := L) w z =
      βˆ‘ i : RelativeAdeleBasisIndex (K := K) (L := L),
        (relativeAdeleCoefficient
            (K := K) (L := L) z i).1 w βŠ—β‚œ[K]
          relativeExtensionBasis (K := K) (L := L) i

The set of places at which a base adele is not in the local valuation ring is finite.

Source context 5 commands

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

open scoped NumberField TensorProduct
open NumberField IsDedekindDomain
noncomputable section
universe u v
variable
    {K : Type u} {L : Type v}
    [Field K] [NumberField K]
    [Field L] [NumberField L] [Algebra K L]
    [FiniteDimensional K L]
theorem finite_adeleNonIntegralPlaces
    (a : NumberField.AdeleRing (π“ž K) K) :
    {w : HeightOneSpectrum (π“ž K) |
      a.2 w βˆ‰ w.adicCompletionIntegers K}.Finite

The exceptional finite places at which a base adele is not in the local valuation ring.

Source context 5 commands

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

open scoped NumberField TensorProduct
open NumberField IsDedekindDomain
noncomputable section
universe u v
variable
    {K : Type u} {L : Type v}
    [Field K] [NumberField K]
    [Field L] [NumberField L] [Algebra K L]
    [FiniteDimensional K L]
def adeleNonIntegralPlaces
    (a : NumberField.AdeleRing (π“ž K) K) :
    Finset (HeightOneSpectrum (π“ž K))
Source context 5 commands

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

open scoped NumberField TensorProduct
open NumberField IsDedekindDomain
noncomputable section
universe u v
variable
    {K : Type u} {L : Type v}
    [Field K] [NumberField K]
    [Field L] [NumberField L] [Algebra K L]
    [FiniteDimensional K L]
theorem mem_adeleNonIntegralPlaces_iff
    (a : NumberField.AdeleRing (π“ž K) K)
    (w : HeightOneSpectrum (π“ž K)) :
    w ∈ adeleNonIntegralPlaces (K := K) a ↔
      a.2 w βˆ‰ w.adicCompletionIntegers K

Away from its exact exceptional finset, a base adele has integral finite component.

Source context 5 commands

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

open scoped NumberField TensorProduct
open NumberField IsDedekindDomain
noncomputable section
universe u v
variable
    {K : Type u} {L : Type v}
    [Field K] [NumberField K]
    [Field L] [NumberField L] [Algebra K L]
    [FiniteDimensional K L]
theorem adele_component_mem_integers_of_notMem
    (a : NumberField.AdeleRing (π“ž K) K)
    (w : HeightOneSpectrum (π“ž K))
    (hw : w βˆ‰ adeleNonIntegralPlaces (K := K) a) :
    a.2 w ∈ w.adicCompletionIntegers K

Exact union of all exceptional coefficient places of a relative adele.

Source context 5 commands

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

open scoped NumberField TensorProduct
open NumberField IsDedekindDomain
noncomputable section
universe u v
variable
    {K : Type u} {L : Type v}
    [Field K] [NumberField K]
    [Field L] [NumberField L] [Algebra K L]
    [FiniteDimensional K L]
def relativeAdeleCoefficientSupport
    (z : RelativeAdeleRing K L) :
    Finset (HeightOneSpectrum (π“ž K))
Source context 6 commands

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

open scoped NumberField TensorProduct
open NumberField IsDedekindDomain
noncomputable section
universe u v
variable
    {K : Type u} {L : Type v}
    [Field K] [NumberField K]
    [Field L] [NumberField L] [Algebra K L]
    [FiniteDimensional K L]
omit [NumberField L] in
theorem mem_relativeAdeleCoefficientSupport_iff
    (z : RelativeAdeleRing K L)
    (w : HeightOneSpectrum (π“ž K)) :
    w ∈ relativeAdeleCoefficientSupport
        (K := K) (L := L) z ↔
      βˆƒ i : RelativeAdeleBasisIndex (K := K) (L := L),
        (relativeAdeleCoefficient
            (K := K) (L := L) z i).2 w βˆ‰
          w.adicCompletionIntegers K

The exact coefficient support of a relative idele contains the exceptional places of the idele and its inverse.

Source context 5 commands

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

open scoped NumberField TensorProduct
open NumberField IsDedekindDomain
noncomputable section
universe u v
variable
    {K : Type u} {L : Type v}
    [Field K] [NumberField K]
    [Field L] [NumberField L] [Algebra K L]
    [FiniteDimensional K L]
def relativeIdeleCoefficientSupport
    (z : RelativeIdeleGroup K L) :
    Finset (HeightOneSpectrum (π“ž K))
Source context 6 commands

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

open scoped NumberField TensorProduct
open NumberField IsDedekindDomain
noncomputable section
universe u v
variable
    {K : Type u} {L : Type v}
    [Field K] [NumberField K]
    [Field L] [NumberField L] [Algebra K L]
    [FiniteDimensional K L]
omit [NumberField L] in
theorem mem_relativeIdeleCoefficientSupport_iff
    (z : RelativeIdeleGroup K L)
    (w : HeightOneSpectrum (π“ž K)) :
    w ∈ relativeIdeleCoefficientSupport
        (K := K) (L := L) z ↔
      (βˆƒ i : RelativeAdeleBasisIndex (K := K) (L := L),
        (relativeAdeleCoefficient
            (K := K) (L := L)
            (z : RelativeAdeleRing K L) i).2 w βˆ‰
          w.adicCompletionIntegers K) ∨
      (βˆƒ i : RelativeAdeleBasisIndex (K := K) (L := L),
        (relativeAdeleCoefficient
            (K := K) (L := L)
            ((z⁻¹ : RelativeIdeleGroup K L) :
              RelativeAdeleRing K L) i).2 w βˆ‰
          w.adicCompletionIntegers K)

Outside the exact coefficient support, every coefficient of both the relative idele and its inverse is integral at the given finite place.

Source context 6 commands

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

open scoped NumberField TensorProduct
open NumberField IsDedekindDomain
noncomputable section
universe u v
variable
    {K : Type u} {L : Type v}
    [Field K] [NumberField K]
    [Field L] [NumberField L] [Algebra K L]
    [FiniteDimensional K L]
omit [NumberField L] in
theorem relativeIdele_coefficients_integral_of_notMem
    (z : RelativeIdeleGroup K L)
    (w : HeightOneSpectrum (π“ž K))
    (hw : w βˆ‰ relativeIdeleCoefficientSupport
      (K := K) (L := L) z) :
    (βˆ€ i : RelativeAdeleBasisIndex (K := K) (L := L),
      (relativeAdeleCoefficient
          (K := K) (L := L)
          (z : RelativeAdeleRing K L) i).2 w ∈
        w.adicCompletionIntegers K) ∧
    (βˆ€ i : RelativeAdeleBasisIndex (K := K) (L := L),
      (relativeAdeleCoefficient
          (K := K) (L := L)
          ((z⁻¹ : RelativeIdeleGroup K L) :
            RelativeAdeleRing K L) i).2 w ∈
        w.adicCompletionIntegers K)

The exact support is the least finset outside which all coefficients of the idele and its inverse are integral.

Source context 6 commands

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

open scoped NumberField TensorProduct
open NumberField IsDedekindDomain
noncomputable section
universe u v
variable
    {K : Type u} {L : Type v}
    [Field K] [NumberField K]
    [Field L] [NumberField L] [Algebra K L]
    [FiniteDimensional K L]
omit [NumberField L] in
theorem relativeIdeleCoefficientSupport_minimal
    (z : RelativeIdeleGroup K L)
    (S : Finset (HeightOneSpectrum (π“ž K)))
    (hS :
      βˆ€ w, w βˆ‰ S β†’
        (βˆ€ i : RelativeAdeleBasisIndex (K := K) (L := L),
          (relativeAdeleCoefficient
              (K := K) (L := L)
              (z : RelativeAdeleRing K L) i).2 w ∈
            w.adicCompletionIntegers K) ∧
        (βˆ€ i : RelativeAdeleBasisIndex (K := K) (L := L),
          (relativeAdeleCoefficient
              (K := K) (L := L)
              ((z⁻¹ : RelativeIdeleGroup K L) :
                RelativeAdeleRing K L) i).2 w ∈
            w.adicCompletionIntegers K)) :
    relativeIdeleCoefficientSupport
        (K := K) (L := L) z βŠ† S

Basis-lattice integrality in the local tensor algebra: all coordinates in the fixed extension basis belong to the valuation ring of K_w.

Source context 6 commands

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

open scoped NumberField TensorProduct
open NumberField IsDedekindDomain
noncomputable section
universe u v
variable
    {K : Type u} {L : Type v}
    [Field K] [NumberField K]
    [Field L] [NumberField L] [Algebra K L]
    [FiniteDimensional K L]
omit [NumberField L] in
def RelativeBasisIntegralAt
    (w : HeightOneSpectrum (π“ž K))
    (x : w.adicCompletion K βŠ—[K] L) : Prop

A local tensor unit is basis-integral when both it and its inverse belong to the local valuation-ring coefficient lattice.

Source context 6 commands

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

open scoped NumberField TensorProduct
open NumberField IsDedekindDomain
noncomputable section
universe u v
variable
    {K : Type u} {L : Type v}
    [Field K] [NumberField K]
    [Field L] [NumberField L] [Algebra K L]
    [FiniteDimensional K L]
omit [NumberField L] in
def RelativeBasisIntegralUnitAt
    (w : HeightOneSpectrum (π“ž K))
    (x : (w.adicCompletion K βŠ—[K] L)Λ£) : Prop

The finite component of a relative idele is given by the evaluated base-adele coefficients.

Source context 6 commands

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

open scoped NumberField TensorProduct
open NumberField IsDedekindDomain
noncomputable section
universe u v
variable
    {K : Type u} {L : Type v}
    [Field K] [NumberField K]
    [Field L] [NumberField L] [Algebra K L]
    [FiniteDimensional K L]
omit [NumberField L] in
theorem relativeIdele_finiteComponent_eq_sum_tmul_coefficients
    (z : RelativeIdeleGroup K L)
    (w : HeightOneSpectrum (π“ž K)) :
    ((RelativeIdeleGroup.finiteComponent
        (K := K) (L := L) w z :
        (w.adicCompletion K βŠ—[K] L)Λ£) :
        w.adicCompletion K βŠ—[K] L) =
      βˆ‘ i : RelativeAdeleBasisIndex (K := K) (L := L),
        (relativeAdeleCoefficient
            (K := K) (L := L)
            (z : RelativeAdeleRing K L) i).2 w βŠ—β‚œ[K]
          relativeExtensionBasis (K := K) (L := L) i

Outside the coefficient support, the actual finite component lies in the local lattice spanned by the chosen extension basis.

Source context 6 commands

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

open scoped NumberField TensorProduct
open NumberField IsDedekindDomain
noncomputable section
universe u v
variable
    {K : Type u} {L : Type v}
    [Field K] [NumberField K]
    [Field L] [NumberField L] [Algebra K L]
    [FiniteDimensional K L]
omit [NumberField L] in
theorem relativeIdele_finiteComponent_basisIntegral_of_notMem
    (z : RelativeIdeleGroup K L)
    (w : HeightOneSpectrum (π“ž K))
    (hw : w βˆ‰ relativeIdeleCoefficientSupport
      (K := K) (L := L) z) :
    RelativeBasisIntegralAt
      (K := K) (L := L) w
      ((RelativeIdeleGroup.finiteComponent
          (K := K) (L := L) w z :
          (w.adicCompletion K βŠ—[K] L)Λ£) :
          w.adicCompletion K βŠ—[K] L)

Outside the same support, the actual finite component of the inverse lies in the same local basis lattice.

Source context 6 commands

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

open scoped NumberField TensorProduct
open NumberField IsDedekindDomain
noncomputable section
universe u v
variable
    {K : Type u} {L : Type v}
    [Field K] [NumberField K]
    [Field L] [NumberField L] [Algebra K L]
    [FiniteDimensional K L]
omit [NumberField L] in
theorem relativeIdele_inverse_finiteComponent_basisIntegral_of_notMem
    (z : RelativeIdeleGroup K L)
    (w : HeightOneSpectrum (π“ž K))
    (hw : w βˆ‰ relativeIdeleCoefficientSupport
      (K := K) (L := L) z) :
    RelativeBasisIntegralAt
      (K := K) (L := L) w
      ((RelativeIdeleGroup.finiteComponent
          (K := K) (L := L) w
          (z⁻¹ : RelativeIdeleGroup K L) :
          (w.adicCompletion K βŠ—[K] L)Λ£) :
          w.adicCompletion K βŠ—[K] L)

Equivalently, the inverse of the actual local unit component lies in the same basis lattice outside the coefficient support.

Source context 6 commands

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

open scoped NumberField TensorProduct
open NumberField IsDedekindDomain
noncomputable section
universe u v
variable
    {K : Type u} {L : Type v}
    [Field K] [NumberField K]
    [Field L] [NumberField L] [Algebra K L]
    [FiniteDimensional K L]
omit [NumberField L] in
theorem relativeIdele_finiteComponent_inv_basisIntegral_of_notMem
    (z : RelativeIdeleGroup K L)
    (w : HeightOneSpectrum (π“ž K))
    (hw : w βˆ‰ relativeIdeleCoefficientSupport
      (K := K) (L := L) z) :
    RelativeBasisIntegralAt
      (K := K) (L := L) w
      ((((RelativeIdeleGroup.finiteComponent
          (K := K) (L := L) w z)⁻¹ :
          (w.adicCompletion K βŠ—[K] L)Λ£) :
          w.adicCompletion K βŠ—[K] L))

Thus the actual local unit component is basis-integral outside the explicit coefficient support.

Source context 6 commands

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

open scoped NumberField TensorProduct
open NumberField IsDedekindDomain
noncomputable section
universe u v
variable
    {K : Type u} {L : Type v}
    [Field K] [NumberField K]
    [Field L] [NumberField L] [Algebra K L]
    [FiniteDimensional K L]
omit [NumberField L] in
theorem relativeIdele_finiteComponent_basisIntegralUnit_of_notMem
    (z : RelativeIdeleGroup K L)
    (w : HeightOneSpectrum (π“ž K))
    (hw : w βˆ‰ relativeIdeleCoefficientSupport
      (K := K) (L := L) z) :
    RelativeBasisIntegralUnitAt
      (K := K) (L := L) w
      (RelativeIdeleGroup.finiteComponent
        (K := K) (L := L) w z)

A source-producing finite-support theorem: one explicit minimal finset simultaneously controls the local basis integrality of the relative idele and its inverse.

Source context 6 commands

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

open scoped NumberField TensorProduct
open NumberField IsDedekindDomain
noncomputable section
universe u v
variable
    {K : Type u} {L : Type v}
    [Field K] [NumberField K]
    [Field L] [NumberField L] [Algebra K L]
    [FiniteDimensional K L]
omit [NumberField L] in
theorem exists_relativeIdele_coefficientSupport
    (z : RelativeIdeleGroup K L) :
    βˆƒ S : Finset (HeightOneSpectrum (π“ž K)),
      (βˆ€ w, w βˆ‰ S β†’
        (βˆ€ i : RelativeAdeleBasisIndex (K := K) (L := L),
          (relativeAdeleCoefficient
              (K := K) (L := L)
              (z : RelativeAdeleRing K L) i).2 w ∈
            w.adicCompletionIntegers K) ∧
        (βˆ€ i : RelativeAdeleBasisIndex (K := K) (L := L),
          (relativeAdeleCoefficient
              (K := K) (L := L)
              ((z⁻¹ : RelativeIdeleGroup K L) :
                RelativeAdeleRing K L) i).2 w ∈
            w.adicCompletionIntegers K)) ∧
      (βˆ€ w, w βˆ‰ S β†’
        RelativeBasisIntegralAt
          (K := K) (L := L) w
          ((RelativeIdeleGroup.finiteComponent
              (K := K) (L := L) w z :
              (w.adicCompletion K βŠ—[K] L)Λ£) :
              w.adicCompletion K βŠ—[K] L) ∧
        RelativeBasisIntegralAt
          (K := K) (L := L) w
          ((((RelativeIdeleGroup.finiteComponent
              (K := K) (L := L) w z)⁻¹ :
              (w.adicCompletion K βŠ—[K] L)Λ£) :
              w.adicCompletion K βŠ—[K] L)))