Module

OpenCurveH1Deck.lean

Nyll.AnabelianGeometry.GeometricFundamentalGroup.OpenCurveH1Deck
1 declaration indexed from sourceView source ↗

Non-surjective actual H¹ pullback on hyperbolic open covers

Actual compactification, interior unramifiedness and boundary Riemann--Hurwitz force a strict increase in actual finite H¹ cardinality. No Euler characteristic or cohomological comparison is an input assumption.

Declarations

AnabelianGeometry.not_surjective_open_finiteH1Pullback
Source context 6 commands

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

noncomputable section
open CategoryTheory AlgebraicGeometry AlgebraicCurve TopologicalSpace NeronModelInfra
open CategoryTheory.PreGaloisCategory EtaleFundamentalGroups
open EtaleFundamentalGroups.Cohomology
namespace AnabelianGeometry
attribute [local instance] CurveModel.isIntegral CurveModel.isProper CurveModel.smooth
theorem not_surjective_open_finiteH1Pullback
    {K F : Type} [Field K] [IsAlgClosed K] [CharZero K]
    [Field F] [Algebra K F]
    (M : CurveModel K F) {X : Scheme}
    [IsIntegral X] [IsNormalIntegral X] [IsLocallyNoetherian X] [CompactSpace X]
    (j : X ⟶ M.C) [IsOpenImmersion j] [QuasiCompact j] [QuasiSeparated j]
    (hboundary : (M.openBoundaryPlaces j).Nonempty)
    (hhyperbolic : 0 <
      2 * (genusFF K F : ℤ) + (M.openBoundaryPlaces_finite j).toFinset.card - 2)
    (W : FiniteEtale X) [IsGalois W] (σ : Aut W) (hσ : σ ≠ 1)
    (n : ℕ+) (hn : 1 < (n : ℕ))
    {Ω : Type} [Field Ω] [IsSepClosed Ω] (geom : Spec (.of Ω) ⟶ W.left) :
    ¬ Function.Surjective (constantCohomologyPullback (X := W.left) (Y := X) W.hom
      (AddCommGrpCat.of (Additive (rootsOfUnity (n : ℕ) K))) 1)