Module

FiniteLocalFamily.lean

Nyll.ClassFieldTheory.GlobalClassFieldTheory.Reciprocity.FiniteLocalFamily
5 declarations indexed from sourceView source ↗

Finite local families of ideles

A finite family of local elements, extended by 1, is the product of its one-place ideles. Applying the global norm-quotient map gives the finite product identity. The quotient map itself factors through idele classes and therefore kills principal ideles.

Declarations

GlobalClassFieldTheory.Reciprocity.prod_finitePlaceIdele_eq_ideleOfFiniteLocalFamily

A finite local family is the product of its one-place ideles.

Source context 7 commands

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

open scoped NumberField BigOperators
open NumberField IsDedekindDomain
open IdeleGroup RelativeIdeleGroup
noncomputable section
namespace GlobalClassFieldTheory
namespace Reciprocity
variable {K : Type*} [Field K] [NumberField K]
theorem prod_finitePlaceIdele_eq_ideleOfFiniteLocalFamily
    (S : Finset (HeightOneSpectrum (𝓞 K)))
    (a : ∀ v : ↥S, (v.1.adicCompletion K)ˣ) :
    (∏ v : ↥S, finitePlaceIdele v.1 (a v)) =
      IdeleGroup.ideleOfFiniteLocalFamily S a
GlobalClassFieldTheory.Reciprocity.map_ideleOfFiniteLocalFamily_eq_prod_local

Applying any multiplicative global symbol to a finite local family gives the product of the one-place symbols.

Source context 7 commands

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

open scoped NumberField BigOperators
open NumberField IsDedekindDomain
open IdeleGroup RelativeIdeleGroup
noncomputable section
namespace GlobalClassFieldTheory
namespace Reciprocity
variable {K : Type*} [Field K] [NumberField K]
theorem map_ideleOfFiniteLocalFamily_eq_prod_local
    {A : Type*} [CommGroup A]
    (f : IdeleGroup K →* A)
    (S : Finset (HeightOneSpectrum (𝓞 K)))
    (a : ∀ v : ↥S, (v.1.adicCompletion K)ˣ) :
    f (IdeleGroup.ideleOfFiniteLocalFamily S a) =
      ∏ v : ↥S, f (finitePlaceIdele v.1 (a v))
GlobalClassFieldTheory.Reciprocity.finiteLocalFamilyIdeleClassGroupIsMulCommutative
Source context 9 commands

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

open scoped NumberField BigOperators
open NumberField IsDedekindDomain
open IdeleGroup RelativeIdeleGroup
noncomputable section
namespace GlobalClassFieldTheory
namespace Reciprocity
variable {K : Type*} [Field K] [NumberField K]
section NormQuotient
variable
    (L : Type*) [Field L] [NumberField L] [Algebra K L]
    [FiniteDimensional K L]
instance finiteLocalFamilyIdeleClassGroupIsMulCommutative :
    IsMulCommutative (IdeleClassGroup K)
GlobalClassFieldTheory.Reciprocity.finiteLocalFamilyIdeleClassGroupCommGroup
Source context 10 commands

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

open scoped NumberField BigOperators
open NumberField IsDedekindDomain
open IdeleGroup RelativeIdeleGroup
noncomputable section
namespace GlobalClassFieldTheory
namespace Reciprocity
variable {K : Type*} [Field K] [NumberField K]
section NormQuotient
variable
    (L : Type*) [Field L] [NumberField L] [Algebra K L]
    [FiniteDimensional K L]
local instance finiteLocalFamilyIdeleClassGroupIsMulCommutative :
    IsMulCommutative (IdeleClassGroup K) :=
  ⟨⟨fun a b => mul_comm a b⟩⟩
instance finiteLocalFamilyIdeleClassGroupCommGroup :
    CommGroup (IdeleClassGroup K)
GlobalClassFieldTheory.Reciprocity.globalNormClass_finiteLocalFamily

The finite-support product formula for the global norm-quotient symbol.

Source context 12 commands

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

open scoped NumberField BigOperators
open NumberField IsDedekindDomain
open IdeleGroup RelativeIdeleGroup
noncomputable section
namespace GlobalClassFieldTheory
namespace Reciprocity
variable {K : Type*} [Field K] [NumberField K]
section NormQuotient
variable
    (L : Type*) [Field L] [NumberField L] [Algebra K L]
    [FiniteDimensional K L]
local instance finiteLocalFamilyIdeleClassGroupIsMulCommutative :
    IsMulCommutative (IdeleClassGroup K) :=
  ⟨⟨fun a b => mul_comm a b⟩⟩
local instance finiteLocalFamilyIdeleClassGroupCommGroup :
    CommGroup (IdeleClassGroup K) :=
  open scoped IsMulCommutative in
  inferInstance
omit [FiniteDimensional K L] in
theorem globalNormClass_finiteLocalFamily
    (S : Finset (HeightOneSpectrum (𝓞 K)))
    (a : ∀ v : ↥S, (v.1.adicCompletion K)ˣ) :
    globalNormClassFromIdele K L
        (IdeleGroup.ideleOfFiniteLocalFamily S a) =
      ∏ v : ↥S,
        globalNormClassFromIdele K L
          (finitePlaceIdele v.1 (a v))