Module

RamifiedOverextension.lean

Nyll.ClassFieldTheory.GlobalClassFieldTheory.Reciprocity.ComplexificationArtin.RamifiedOverextension
21 declarations indexed from sourceView source ↗

The quadratic overextension at a ramified real place

This module constructs the real fixed field of complex conjugation, the quadratic overextension above it, and the faithful cyclotomic restriction.

Declarations

GlobalClassFieldTheory.Reciprocity.ramifiedInfinitePlaceRealFixedField

The base K' in the archimedean overextension: the fixed field of complex conjugation in L(i).

Source context 8 commands

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

open scoped IsMulCommutative
open NumberField
noncomputable section
namespace GlobalClassFieldTheory
namespace Reciprocity
attribute [local instance]
  infinitePlaceComplexificationOverfieldRationalAlgebra
section ComplexConjugationOverextension
variable
    {K L : Type}
    [Field K] [NumberField K]
    [Field L] [NumberField L] [Algebra K L]
    [FiniteDimensional K L] [IsAbelianGalois K L]
def ramifiedInfinitePlaceRealFixedField
    (v : InfinitePlace K)
    (hRamified :
      (chosenInfinitePlaceAbove (L := L) v).IsRamified K) :
    IntermediateField ℚ
      (infinitePlaceComplexificationOverfield
        (K := K) (L := L) v)
GlobalClassFieldTheory.Reciprocity.ramifiedInfinitePlaceOverfieldConjugation_fixes_base

Ambient complex conjugation on the overfield fixes the embedded base field at a ramified real place.

Source context 9 commands

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

open scoped IsMulCommutative
open NumberField
noncomputable section
namespace GlobalClassFieldTheory
namespace Reciprocity
attribute [local instance]
  infinitePlaceComplexificationOverfieldRationalAlgebra
section ComplexConjugationOverextension
variable
    {K L : Type}
    [Field K] [NumberField K]
    [Field L] [NumberField L] [Algebra K L]
    [FiniteDimensional K L] [IsAbelianGalois K L]
omit [FiniteDimensional K L] in
theorem ramifiedInfinitePlaceOverfieldConjugation_fixes_base
    (v : InfinitePlace K)
    (hRamified :
      (chosenInfinitePlaceAbove (L := L) v).IsRamified K)
    (x : K) :
    ramifiedInfinitePlaceOverfieldConjugation
        (K := K) (L := L) v hRamified
        (algebraMap K
          (infinitePlaceComplexificationOverfield
            (K := K) (L := L) v) x) =
      algebraMap K
        (infinitePlaceComplexificationOverfield
          (K := K) (L := L) v) x
GlobalClassFieldTheory.Reciprocity.ramifiedInfinitePlaceRealFixedFieldEmbedding

The compatible embedding K → K' into the real fixed field.

Source context 8 commands

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

open scoped IsMulCommutative
open NumberField
noncomputable section
namespace GlobalClassFieldTheory
namespace Reciprocity
attribute [local instance]
  infinitePlaceComplexificationOverfieldRationalAlgebra
section ComplexConjugationOverextension
variable
    {K L : Type}
    [Field K] [NumberField K]
    [Field L] [NumberField L] [Algebra K L]
    [FiniteDimensional K L] [IsAbelianGalois K L]
def ramifiedInfinitePlaceRealFixedFieldEmbedding
    (v : InfinitePlace K)
    (hRamified :
      (chosenInfinitePlaceAbove (L := L) v).IsRamified K) :
    K →ₐ[ℚ]
      ramifiedInfinitePlaceRealFixedField
        (K := K) (L := L) v hRamified
GlobalClassFieldTheory.Reciprocity.ramifiedInfinitePlaceRealFixedFieldEmbedding_coe

The fixed-field embedding agrees with the original base-field algebra map after coercion to the overfield.

Source context 9 commands

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

open scoped IsMulCommutative
open NumberField
noncomputable section
namespace GlobalClassFieldTheory
namespace Reciprocity
attribute [local instance]
  infinitePlaceComplexificationOverfieldRationalAlgebra
section ComplexConjugationOverextension
variable
    {K L : Type}
    [Field K] [NumberField K]
    [Field L] [NumberField L] [Algebra K L]
    [FiniteDimensional K L] [IsAbelianGalois K L]
omit [FiniteDimensional K L] in
theorem ramifiedInfinitePlaceRealFixedFieldEmbedding_coe
    (v : InfinitePlace K)
    (hRamified :
      (chosenInfinitePlaceAbove (L := L) v).IsRamified K)
    (x : K) :
    ((ramifiedInfinitePlaceRealFixedFieldEmbedding
        (K := K) (L := L) v hRamified x :
      ramifiedInfinitePlaceRealFixedField
        (K := K) (L := L) v hRamified) :
      infinitePlaceComplexificationOverfield
        (K := K) (L := L) v) =
      algebraMap K
        (infinitePlaceComplexificationOverfield
          (K := K) (L := L) v) x
GlobalClassFieldTheory.Reciprocity.ramifiedInfinitePlaceRealFixedField_algebra
Source context 8 commands

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

open scoped IsMulCommutative
open NumberField
noncomputable section
namespace GlobalClassFieldTheory
namespace Reciprocity
attribute [local instance]
  infinitePlaceComplexificationOverfieldRationalAlgebra
section ComplexConjugationOverextension
variable
    {K L : Type}
    [Field K] [NumberField K]
    [Field L] [NumberField L] [Algebra K L]
    [FiniteDimensional K L] [IsAbelianGalois K L]
instance
    ramifiedInfinitePlaceRealFixedField_algebra
    (v : InfinitePlace K)
    (hRamified :
      (chosenInfinitePlaceAbove (L := L) v).IsRamified K) :
    Algebra K
      (ramifiedInfinitePlaceRealFixedField
        (K := K) (L := L) v hRamified)
GlobalClassFieldTheory.Reciprocity.ramifiedInfinitePlaceRealFixedField_ratScalarTower
Source context 8 commands

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

open scoped IsMulCommutative
open NumberField
noncomputable section
namespace GlobalClassFieldTheory
namespace Reciprocity
attribute [local instance]
  infinitePlaceComplexificationOverfieldRationalAlgebra
section ComplexConjugationOverextension
variable
    {K L : Type}
    [Field K] [NumberField K]
    [Field L] [NumberField L] [Algebra K L]
    [FiniteDimensional K L] [IsAbelianGalois K L]
instance ramifiedInfinitePlaceRealFixedField_ratScalarTower
    (v : InfinitePlace K)
    (hRamified :
      (chosenInfinitePlaceAbove (L := L) v).IsRamified K) :
    IsScalarTower ℚ K
      (ramifiedInfinitePlaceRealFixedField
        (K := K) (L := L) v hRamified)
GlobalClassFieldTheory.Reciprocity.ramifiedInfinitePlaceRealFixedField_scalarTower
Source context 8 commands

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

open scoped IsMulCommutative
open NumberField
noncomputable section
namespace GlobalClassFieldTheory
namespace Reciprocity
attribute [local instance]
  infinitePlaceComplexificationOverfieldRationalAlgebra
section ComplexConjugationOverextension
variable
    {K L : Type}
    [Field K] [NumberField K]
    [Field L] [NumberField L] [Algebra K L]
    [FiniteDimensional K L] [IsAbelianGalois K L]
instance ramifiedInfinitePlaceRealFixedField_scalarTower
    (v : InfinitePlace K)
    (hRamified :
      (chosenInfinitePlaceAbove (L := L) v).IsRamified K) :
    IsScalarTower K
      (ramifiedInfinitePlaceRealFixedField
        (K := K) (L := L) v hRamified)
      (infinitePlaceComplexificationOverfield
        (K := K) (L := L) v)
GlobalClassFieldTheory.Reciprocity.ramifiedInfinitePlaceRealFixedField_finiteDimensional
Source context 9 commands

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

open scoped IsMulCommutative
open NumberField
noncomputable section
namespace GlobalClassFieldTheory
namespace Reciprocity
attribute [local instance]
  infinitePlaceComplexificationOverfieldRationalAlgebra
section ComplexConjugationOverextension
variable
    {K L : Type}
    [Field K] [NumberField K]
    [Field L] [NumberField L] [Algebra K L]
    [FiniteDimensional K L] [IsAbelianGalois K L]
omit [NumberField K] [FiniteDimensional K L] in
theorem
    ramifiedInfinitePlaceRealFixedField_finiteDimensional
    (v : InfinitePlace K)
    (hRamified :
      (chosenInfinitePlaceAbove (L := L) v).IsRamified K) :
    FiniteDimensional ℚ
      (ramifiedInfinitePlaceRealFixedField
        (K := K) (L := L) v hRamified)
GlobalClassFieldTheory.Reciprocity.ramifiedInfinitePlaceRealFixedField_numberField
Source context 8 commands

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

open scoped IsMulCommutative
open NumberField
noncomputable section
namespace GlobalClassFieldTheory
namespace Reciprocity
attribute [local instance]
  infinitePlaceComplexificationOverfieldRationalAlgebra
section ComplexConjugationOverextension
variable
    {K L : Type}
    [Field K] [NumberField K]
    [Field L] [NumberField L] [Algebra K L]
    [FiniteDimensional K L] [IsAbelianGalois K L]
instance ramifiedInfinitePlaceRealFixedField_numberField
    (v : InfinitePlace K)
    (hRamified :
      (chosenInfinitePlaceAbove (L := L) v).IsRamified K) :
    NumberField
      (ramifiedInfinitePlaceRealFixedField
        (K := K) (L := L) v hRamified)
GlobalClassFieldTheory.Reciprocity.ramifiedInfinitePlaceRealFixedField_finiteDimensional_over_base
Source context 9 commands

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

open scoped IsMulCommutative
open NumberField
noncomputable section
namespace GlobalClassFieldTheory
namespace Reciprocity
attribute [local instance]
  infinitePlaceComplexificationOverfieldRationalAlgebra
section ComplexConjugationOverextension
variable
    {K L : Type}
    [Field K] [NumberField K]
    [Field L] [NumberField L] [Algebra K L]
    [FiniteDimensional K L] [IsAbelianGalois K L]
omit [FiniteDimensional K L] in
theorem
    ramifiedInfinitePlaceRealFixedField_finiteDimensional_over_base
    (v : InfinitePlace K)
    (hRamified :
      (chosenInfinitePlaceAbove (L := L) v).IsRamified K) :
    FiniteDimensional K
      (ramifiedInfinitePlaceRealFixedField
        (K := K) (L := L) v hRamified)
GlobalClassFieldTheory.Reciprocity.ramifiedInfinitePlaceRealFixedField_isAbelianGalois_over_base
Source context 8 commands

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

open scoped IsMulCommutative
open NumberField
noncomputable section
namespace GlobalClassFieldTheory
namespace Reciprocity
attribute [local instance]
  infinitePlaceComplexificationOverfieldRationalAlgebra
section ComplexConjugationOverextension
variable
    {K L : Type}
    [Field K] [NumberField K]
    [Field L] [NumberField L] [Algebra K L]
    [FiniteDimensional K L] [IsAbelianGalois K L]
instance
    ramifiedInfinitePlaceRealFixedField_isAbelianGalois_over_base
    (v : InfinitePlace K)
    (hRamified :
      (chosenInfinitePlaceAbove (L := L) v).IsRamified K) :
    IsAbelianGalois K
      (ramifiedInfinitePlaceRealFixedField
        (K := K) (L := L) v hRamified)
GlobalClassFieldTheory.Reciprocity.ramifiedInfinitePlaceOverfield_finiteDimensional_over_fixed
Source context 9 commands

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

open scoped IsMulCommutative
open NumberField
noncomputable section
namespace GlobalClassFieldTheory
namespace Reciprocity
attribute [local instance]
  infinitePlaceComplexificationOverfieldRationalAlgebra
section ComplexConjugationOverextension
variable
    {K L : Type}
    [Field K] [NumberField K]
    [Field L] [NumberField L] [Algebra K L]
    [FiniteDimensional K L] [IsAbelianGalois K L]
omit [NumberField K] [FiniteDimensional K L] in
theorem
    ramifiedInfinitePlaceOverfield_finiteDimensional_over_fixed
    (v : InfinitePlace K)
    (hRamified :
      (chosenInfinitePlaceAbove (L := L) v).IsRamified K) :
    FiniteDimensional
      (ramifiedInfinitePlaceRealFixedField
        (K := K) (L := L) v hRamified)
      (infinitePlaceComplexificationOverfield
        (K := K) (L := L) v)
GlobalClassFieldTheory.Reciprocity.ramifiedInfinitePlaceOverextension_isGalois
Source context 9 commands

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

open scoped IsMulCommutative
open NumberField
noncomputable section
namespace GlobalClassFieldTheory
namespace Reciprocity
attribute [local instance]
  infinitePlaceComplexificationOverfieldRationalAlgebra
section ComplexConjugationOverextension
variable
    {K L : Type}
    [Field K] [NumberField K]
    [Field L] [NumberField L] [Algebra K L]
    [FiniteDimensional K L] [IsAbelianGalois K L]
omit [NumberField K] [FiniteDimensional K L] in
theorem ramifiedInfinitePlaceOverextension_isGalois
    (v : InfinitePlace K)
    (hRamified :
      (chosenInfinitePlaceAbove (L := L) v).IsRamified K) :
    IsGalois
      (ramifiedInfinitePlaceRealFixedField
        (K := K) (L := L) v hRamified)
      (infinitePlaceComplexificationOverfield
        (K := K) (L := L) v)
GlobalClassFieldTheory.Reciprocity.ramifiedInfinitePlaceOverextension_isAbelianGalois
Source context 8 commands

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

open scoped IsMulCommutative
open NumberField
noncomputable section
namespace GlobalClassFieldTheory
namespace Reciprocity
attribute [local instance]
  infinitePlaceComplexificationOverfieldRationalAlgebra
section ComplexConjugationOverextension
variable
    {K L : Type}
    [Field K] [NumberField K]
    [Field L] [NumberField L] [Algebra K L]
    [FiniteDimensional K L] [IsAbelianGalois K L]
instance
    ramifiedInfinitePlaceOverextension_isAbelianGalois
    (v : InfinitePlace K)
    (hRamified :
      (chosenInfinitePlaceAbove (L := L) v).IsRamified K) :
    IsAbelianGalois
      (ramifiedInfinitePlaceRealFixedField
        (K := K) (L := L) v hRamified)
      (infinitePlaceComplexificationOverfield
        (K := K) (L := L) v)
GlobalClassFieldTheory.Reciprocity.ramifiedInfinitePlaceOverextensionConjugation

The distinguished nontrivial automorphism of the quadratic overextension L(i)/K', obtained from ambient complex conjugation.

Source context 8 commands

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

open scoped IsMulCommutative
open NumberField
noncomputable section
namespace GlobalClassFieldTheory
namespace Reciprocity
attribute [local instance]
  infinitePlaceComplexificationOverfieldRationalAlgebra
section ComplexConjugationOverextension
variable
    {K L : Type}
    [Field K] [NumberField K]
    [Field L] [NumberField L] [Algebra K L]
    [FiniteDimensional K L] [IsAbelianGalois K L]
def ramifiedInfinitePlaceOverextensionConjugation
    (v : InfinitePlace K)
    (hRamified :
      (chosenInfinitePlaceAbove (L := L) v).IsRamified K) :
    Gal(
      (infinitePlaceComplexificationOverfield
        (K := K) (L := L) v) /
      (ramifiedInfinitePlaceRealFixedField
        (K := K) (L := L) v hRamified))
GlobalClassFieldTheory.Reciprocity.ramifiedInfinitePlaceOverextensionConjugation_apply

The distinguished overextension automorphism is the restriction of ambient complex conjugation.

Source context 9 commands

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

open scoped IsMulCommutative
open NumberField
noncomputable section
namespace GlobalClassFieldTheory
namespace Reciprocity
attribute [local instance]
  infinitePlaceComplexificationOverfieldRationalAlgebra
section ComplexConjugationOverextension
variable
    {K L : Type}
    [Field K] [NumberField K]
    [Field L] [NumberField L] [Algebra K L]
    [FiniteDimensional K L] [IsAbelianGalois K L]
omit [NumberField K] [FiniteDimensional K L] in
theorem ramifiedInfinitePlaceOverextensionConjugation_apply
    (v : InfinitePlace K)
    (hRamified :
      (chosenInfinitePlaceAbove (L := L) v).IsRamified K)
    (z :
      infinitePlaceComplexificationOverfield
        (K := K) (L := L) v) :
    ramifiedInfinitePlaceOverextensionConjugation
        (K := K) (L := L) v hRamified z =
      ramifiedInfinitePlaceOverfieldConjugation
        (K := K) (L := L) v hRamified z
GlobalClassFieldTheory.Reciprocity.ramifiedInfinitePlaceOverextension_eq_one_or_conjugation

Every automorphism of the overextension is either the identity or the distinguished complex conjugation.

Source context 9 commands

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

open scoped IsMulCommutative
open NumberField
noncomputable section
namespace GlobalClassFieldTheory
namespace Reciprocity
attribute [local instance]
  infinitePlaceComplexificationOverfieldRationalAlgebra
section ComplexConjugationOverextension
variable
    {K L : Type}
    [Field K] [NumberField K]
    [Field L] [NumberField L] [Algebra K L]
    [FiniteDimensional K L] [IsAbelianGalois K L]
omit [NumberField K] [FiniteDimensional K L] in
theorem ramifiedInfinitePlaceOverextension_eq_one_or_conjugation
    (v : InfinitePlace K)
    (hRamified :
      (chosenInfinitePlaceAbove (L := L) v).IsRamified K)
    (σ : Gal((infinitePlaceComplexificationOverfield
      (K := K) (L := L) v)/(ramifiedInfinitePlaceRealFixedField
      (K := K) (L := L) v hRamified))) :
    σ = 1 ∨
      σ =
        ramifiedInfinitePlaceOverextensionConjugation
          (K := K) (L := L) v hRamified
GlobalClassFieldTheory.Reciprocity.ramifiedInfinitePlaceOverextensionCyclotomicRestriction

Restriction of the quadratic overextension Galois group to the rational fourth-root factor.

Source context 9 commands

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

open scoped IsMulCommutative
open NumberField
noncomputable section
namespace GlobalClassFieldTheory
namespace Reciprocity
attribute [local instance]
  infinitePlaceComplexificationOverfieldRationalAlgebra
section ComplexConjugationOverextension
variable
    {K L : Type}
    [Field K] [NumberField K]
    [Field L] [NumberField L] [Algebra K L]
    [FiniteDimensional K L] [IsAbelianGalois K L]
attribute [local instance]
  rationalComplexificationCyclotomicField_isAbelianGalois
def
    ramifiedInfinitePlaceOverextensionCyclotomicRestriction
    (v : InfinitePlace K)
    (hRamified :
      (chosenInfinitePlaceAbove (L := L) v).IsRamified K) :
    Gal(
      (infinitePlaceComplexificationOverfield
        (K := K) (L := L) v) /
      (ramifiedInfinitePlaceRealFixedField
        (K := K) (L := L) v hRamified)) →*
      Gal(rationalComplexificationCyclotomicField / ℚ)
GlobalClassFieldTheory.Reciprocity.ramifiedInfinitePlaceOverfieldConjugation_map_zeta_ne

The mapped primitive fourth root in the overfield is not fixed by ambient complex conjugation.

Source context 10 commands

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

open scoped IsMulCommutative
open NumberField
noncomputable section
namespace GlobalClassFieldTheory
namespace Reciprocity
attribute [local instance]
  infinitePlaceComplexificationOverfieldRationalAlgebra
section ComplexConjugationOverextension
variable
    {K L : Type}
    [Field K] [NumberField K]
    [Field L] [NumberField L] [Algebra K L]
    [FiniteDimensional K L] [IsAbelianGalois K L]
attribute [local instance]
  rationalComplexificationCyclotomicField_isAbelianGalois
omit [NumberField K] [FiniteDimensional K L] in
theorem ramifiedInfinitePlaceOverfieldConjugation_map_zeta_ne
    (v : InfinitePlace K)
    (hRamified :
      (chosenInfinitePlaceAbove (L := L) v).IsRamified K) :
    ramifiedInfinitePlaceOverfieldConjugation
        (K := K) (L := L) v hRamified
        (algebraMap rationalComplexificationCyclotomicField
          (infinitePlaceComplexificationOverfield
            (K := K) (L := L) v)
          (IsCyclotomicExtension.zeta
            4 ℚ rationalComplexificationCyclotomicField)) ≠
      algebraMap rationalComplexificationCyclotomicField
        (infinitePlaceComplexificationOverfield
          (K := K) (L := L) v)
        (IsCyclotomicExtension.zeta
          4 ℚ rationalComplexificationCyclotomicField)
GlobalClassFieldTheory.Reciprocity.ramifiedInfinitePlaceOverextensionCyclotomicRestriction_conjugation_ne_one

The distinguished overextension conjugation restricts nontrivially to the rational fourth-root factor.

Source context 10 commands

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

open scoped IsMulCommutative
open NumberField
noncomputable section
namespace GlobalClassFieldTheory
namespace Reciprocity
attribute [local instance]
  infinitePlaceComplexificationOverfieldRationalAlgebra
section ComplexConjugationOverextension
variable
    {K L : Type}
    [Field K] [NumberField K]
    [Field L] [NumberField L] [Algebra K L]
    [FiniteDimensional K L] [IsAbelianGalois K L]
attribute [local instance]
  rationalComplexificationCyclotomicField_isAbelianGalois
omit [NumberField K] [FiniteDimensional K L] in
theorem
    ramifiedInfinitePlaceOverextensionCyclotomicRestriction_conjugation_ne_one
    (v : InfinitePlace K)
    (hRamified :
      (chosenInfinitePlaceAbove (L := L) v).IsRamified K) :
    ramifiedInfinitePlaceOverextensionCyclotomicRestriction
        (K := K) (L := L) v hRamified
        (ramifiedInfinitePlaceOverextensionConjugation
          (K := K) (L := L) v hRamified) ≠
      1
GlobalClassFieldTheory.Reciprocity.ramifiedInfinitePlaceOverextensionCyclotomicRestriction_injective

Restriction to the rational fourth-root factor is injective on the quadratic overextension.

Source context 10 commands

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

open scoped IsMulCommutative
open NumberField
noncomputable section
namespace GlobalClassFieldTheory
namespace Reciprocity
attribute [local instance]
  infinitePlaceComplexificationOverfieldRationalAlgebra
section ComplexConjugationOverextension
variable
    {K L : Type}
    [Field K] [NumberField K]
    [Field L] [NumberField L] [Algebra K L]
    [FiniteDimensional K L] [IsAbelianGalois K L]
attribute [local instance]
  rationalComplexificationCyclotomicField_isAbelianGalois
omit [NumberField K] [FiniteDimensional K L] in
theorem
    ramifiedInfinitePlaceOverextensionCyclotomicRestriction_injective
    (v : InfinitePlace K)
    (hRamified :
      (chosenInfinitePlaceAbove (L := L) v).IsRamified K) :
    Function.Injective
      (ramifiedInfinitePlaceOverextensionCyclotomicRestriction
        (K := K) (L := L) v hRamified)