Module

Construction.lean

Nyll.ClassFieldTheory.GlobalClassFieldTheory.GlobalClassFields.ClosedFiniteIndexClassFieldReciprocity.Algebraic.Construction
2 declarations indexed from sourceView source ↗

Underlying algebraic closed finite-index reciprocity

The algebraic equivalence is obtained by forgetting topology from the named continuous provider. This avoids a second specialization of the full finite global reciprocity instance tower.

Declarations

GlobalClassFieldTheory.GlobalClassFields.closedFiniteIndexAlgebraicClassGroupIsMulCommutative

Canonical class-group commutativity supplies normality of the defining subgroup.

Source context 4 commands

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

open scoped IsMulCommutative NumberField
noncomputable section
namespace GlobalClassFieldTheory
namespace GlobalClassFields
theorem closedFiniteIndexAlgebraicClassGroupIsMulCommutative
    (F : Type) [Field F] [NumberField F] :
    IsMulCommutative (IdeleClassGroup F)
GlobalClassFieldTheory.GlobalClassFields.closedFiniteIndexClassFieldGaloisEquivNormQuotient

Global reciprocity for the selected class field, stated over the original number field and directly modulo its defining subgroup.

Source context 6 commands

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

open scoped IsMulCommutative NumberField
noncomputable section
namespace GlobalClassFieldTheory
namespace GlobalClassFields
attribute [local instance] closedFiniteIndexAlgebraicClassGroupIsMulCommutative
variable {K : Type} [Field K] [NumberField K]
abbrev closedFiniteIndexClassFieldGaloisEquivNormQuotient
    (H : Subgroup (IdeleClassGroup K))
    (hclosed : IsClosed (H : Set (IdeleClassGroup K)))
    [H.FiniteIndex] :
    Gal((closedFiniteIndexClassField
          (K := K) H hclosed) / K) ≃*
      IdeleClassGroup K ⧸ H