Module

MixedCharOpenSubgroupFaithfulness.lean

Nyll.Yamaguchi26AbfaithfulGalois.Kummer.Concrete.MixedCharOpenSubgroupFaithfulness
1 declaration indexed from sourceView source ↗

Complete mixed-characteristic faithfulness for open normal subgroups

Infinite Galois correspondence constructs the finite Galois fixed field of an open normal subgroup. Its degree is the given index, so the established field detection applies to the subgroup's actual pro-p residual quotient.

Declarations

ClassFieldTower.Martinet.Shafarevich.mixedChar_openSubgroup_residualAbelianization_faithful

An open normal subgroup of any prime index has faithful quotient conjugation on its abelianized pro-p residual quotient.

Source context 3 commands

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

namespace ClassFieldTower.Martinet.Shafarevich
open ProCGroups ProCGroups.ProC
attribute [local instance] KummerTheory.fixingSubgroup_normal
theorem mixedChar_openSubgroup_residualAbelianization_faithful
    {F Ω : Type*} [Field F] [Field Ω] [Algebra F Ω] [IsAlgClosure F Ω] [CharZero F]
    (vF : _root_.Valuation F (WithZero (Multiplicative ℤ)))
    [ValuationTheory.DiscreteValuationField.Valuation.IsCompleteDiscrete vF]
    (p : ℕ) [Fact p.Prime]
    [hres : CharP (IsLocalRing.ResidueField vF.valuationSubring) p]
    (N : Subgroup Gal(Ω/F)) [N.Normal]
    (hN : IsOpen (N : Set Gal(Ω/F))) {r : ℕ} [Fact r.Prime]
    (hindex : N.index = r) :
    Function.Injective
      (residualAbelianizationQuotientConjugation
        (FiniteGroupClass.pGroup_fullFormation p) N (N.isClosed_of_isOpen hN))