Module

FixedInclusion.lean

Nyll.Yamaguchi26AbfaithfulGalois.FormalHilbert90.FixedInclusion
2 declarations indexed from sourceView source ↗

Inclusion of fixed primary classes

Under relative formal Hilbert 90, globally fixed primary classes inject into the primary abelianization of the ambient group.

Declarations

Yamaguchi26AbfaithfulGalois.primaryFixed_eq_one_of_inclusion_eq_one
Source context 3 commands

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

namespace Yamaguchi26AbfaithfulGalois
open ProCGroups.Abelian ProCGroups.ProC
universe u
theorem primaryFixed_eq_one_of_inclusion_eq_one
    {ℓ : ℕ} [Fact ℓ.Prime]
    {G : Type u} [Group G] [TopologicalSpace G] [IsTopologicalGroup G]
    [CompactSpace G] [T2Space G] [TotallyDisconnectedSpace G]
    (D : Subgroup G) [D.Normal] (hD : IsClosed (D : Set G))
    (θ : Orientation ℓ G) (hDθ : D ≤ θ.toMonoidHom.ker)
    (hLift : RelativeFormalHilbert90 D θ)
    (a : PrimaryAbelianization ℓ D)
    (ha : a ∈ primaryFixedSubgroup ℓ D hD (⊤ : Subgroup G))
    (hzero : primaryInclusionMap ℓ D hD a = 1) : a = 1
Yamaguchi26AbfaithfulGalois.primaryInclusionMap_injective_on_fixed

Global fixed primary classes inject into the primary abelianization of the ambient group under the relative formal Hilbert 90 hypothesis.

Source context 3 commands

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

namespace Yamaguchi26AbfaithfulGalois
open ProCGroups.Abelian ProCGroups.ProC
universe u
theorem primaryInclusionMap_injective_on_fixed
    {ℓ : ℕ} [Fact ℓ.Prime]
    {G : Type u} [Group G] [TopologicalSpace G] [IsTopologicalGroup G]
    [CompactSpace G] [T2Space G] [TotallyDisconnectedSpace G]
    (D : Subgroup G) [D.Normal] (hD : IsClosed (D : Set G))
    (θ : Orientation ℓ G) (hDθ : D ≤ θ.toMonoidHom.ker)
    (hLift : RelativeFormalHilbert90 D θ) :
    Function.Injective
      (fun a : primaryFixedSubgroup ℓ D hD (⊤ : Subgroup G) =>
        primaryInclusionMap ℓ D hD (a : PrimaryAbelianization ℓ D)) := by
  intro a b hab
  change primaryInclusionMap ℓ D hD (a : PrimaryAbelianization ℓ D) =
    primaryInclusionMap ℓ D hD (b : PrimaryAbelianization ℓ D) at hab
  apply Subtype.ext
  apply mul_inv_eq_one.mp
  apply primaryFixed_eq_one_of_inclusion_eq_one D hD θ hDθ hLift
  · exact (primaryFixedSubgroup ℓ D hD (⊤ : Subgroup G)).mul_mem a.property
      ((primaryFixedSubgroup ℓ D hD (⊤ : Subgroup G)).inv_mem b.property)
  · rw [map_mul, map_inv, hab, mul_inv_cancel]