Module

ProsolvableBoundaryExtensions.lean

Nyll.EtaleFundamentalGroups.GaloisCovers.ProsolvableBoundaryExtensions
1 declaration indexed from sourceView source ↗

Prosolvable comparison from actual boundary-cover extensions

This is the public categorical endpoint of the boundary argument. It does not assume injectivity, essential surjectivity, or the desired prosolvable comparison. Its input is an actual finite-etale extension object, together with its pullback isomorphism, for every finite abelian Galois cover occurring over an open-normal pullback component.

Declarations

AlgebraicGeometry.FiniteEtale.prosolvableBoundaryEquivOfPullbackModelExtensions

Actual extensions of all finite abelian covers over the geometric open-normal pullback models identify the maximal prosolvable quotients across the boundary complement.

Source context 7 commands

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

noncomputable section
open CategoryTheory
open CategoryTheory.PreGaloisCategory
open ProCGroups.FiniteStepSolvableQuotients
open scoped ProCGroupsSolvableQuotients
namespace AlgebraicGeometry.FiniteEtale
universe u
def prosolvableBoundaryEquivOfPullbackModelExtensions
    {X : Scheme.{u}} [IsIntegral X] [IsNormalIntegral X]
    [IsLocallyNoetherian X]
    (D : X.EffectiveCartierDivisor)
    [ConnectedSpace D.1.supportComplement]
    {Omega : Type u} [Field Omega] [IsSepClosed Omega]
    (xi : Spec (.of Omega) ⟶ D.1.supportComplement)
    (extend : ∀
      (U : OpenNormalSubgroup
        π₁ᵉᵗ(xi ≫ D.1.supportComplement.ι))
      (W : FiniteEtale
        (openNormalPullbackModel D.1.supportComplement.ι xi U).sourceScheme)
      (_hW : IsGalois W),
      IsMulCommutative (Aut W) →
        Σ Z : FiniteEtale
          (openNormalPullbackModel D.1.supportComplement.ι xi U).targetScheme,
          (pullback
            (openNormalPullbackModel D.1.supportComplement.ι xi U).hom).obj Z ≅ W) :
    (π₁ᵉᵗ(xi) ⧸ ProCGroups.ProC.proCResidualCore
        ProCGroups.FiniteGroupClass.solvable π₁ᵉᵗ(xi)) ≃ₜ*
      (π₁ᵉᵗ(xi ≫ D.1.supportComplement.ι) ⧸
        ProCGroups.ProC.proCResidualCore ProCGroups.FiniteGroupClass.solvable
          π₁ᵉᵗ(xi ≫ D.1.supportComplement.ι))