Module

RigidifiedLineBundle_exists_isClosedImmersion_lfp_chart_iff_of_descent.lean

Nyll.JacobianVarieties.Picard.RigidifiedLineBundle_exists_isClosedImmersion_lfp_chart_iff_of_descent
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A closed immersion chart obtained by descent

A descended closed immersion representing trivializations pulls back to a chart for the original rigidified line bundle. Noetherianity gives finite presentation.

Imports19
Imported by2

Declarations

AlgebraicGeometry.RelPicard.RigidifiedLineBundle.exists_isClosedImmersion_lfp_chart_iff_of_descent
Source context 9 commands

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

section ProofImplementation
namespace AlgebraicGeometry.RelPicard.RigidifiedLineBundle
open _root_.CategoryTheory
open _root_.CategoryTheory.Limits
open _root_.CategoryTheory.MonoidalCategory
open _root_.AlgebraicGeometry
open _root_.NeronModelInfra
open _root_.GoodReductionJacobian
open _root_.AlgebraicGeometry.Polarisation
theorem exists_isClosedImmersion_lfp_chart_iff_of_descent
    {R : Type} [CommRing R] {A : Scheme.{0}} {f : A ⟶ Spec (CommRingCat.of R)}
    (L : RelativeGroupLaw R f)
    {X : Scheme.{0}} (g : X ⟶ Spec (CommRingCat.of R))
    (M : RigidifiedLineBundle f (L.one (𝟙 (Spec (CommRingCat.of R)))) g) (U : X.affineOpens)
    (R₀ : Type) [CommRing R₀] [IsNoetherianRing R₀] (φ : R₀ →+* R)
    (A₀ : Scheme.{0}) (f₀ : A₀ ⟶ Spec (CommRingCat.of R₀)) (L₀ : RelativeGroupLaw R₀ f₀)
    (X₀ : Scheme.{0}) (g₀ : X₀ ⟶ Spec (CommRingCat.of R₀)) [LocallyOfFiniteType g₀]
    (M₀ : RigidifiedLineBundle f₀ (L₀.one (𝟙 (Spec (CommRingCat.of R₀)))) g₀)
    (a : A ⟶ A₀) (ha : IsPullback a f f₀ (Spec.map (CommRingCat.ofHom φ)))
    (u : ((U : X.Opens) : Scheme.{0}) ⟶ X₀)
    (hu : IsPullback u ((U : X.Opens).ι ≫ g) g₀ (Spec.map (CommRingCat.ofHom φ)))
    (hM : Nonempty ((M.pullbackAlong
      (⟨(U : X.Opens).ι, rfl⟩ : SchemeHomOver ((U : X.Opens).ι ≫ g) g)).L ≅
      (Scheme.Modules.pullback
        (pullback.map f ((U : X.Opens).ι ≫ g) f₀ g₀ a u
          (Spec.map (CommRingCat.ofHom φ)) ha.w.symm hu.w.symm)).obj M₀.L))
    (Z₀ : Scheme.{0}) (ι₀ : Z₀ ⟶ X₀) (hι₀ : IsClosedImmersion ι₀)
    (hZ₀ : ∀ {T : Scheme.{0}} (t : T ⟶ Spec (CommRingCat.of R₀)) (ψ : SchemeHomOver t g₀),
        Nonempty ((M₀.pullbackAlong ψ).L ≅
            (RigidifiedLineBundle.unit (c := f₀)
              (ε := L₀.one (𝟙 (Spec (CommRingCat.of R₀)))) t).L) ↔
          ∃ ψ₀ : T ⟶ Z₀, ψ₀ ≫ ι₀ = ψ.1) :
    ∃ (ZU : Scheme.{0}) (ιU : ZU ⟶ ((U : X.Opens) : Scheme.{0})),
        IsClosedImmersion ιU ∧ LocallyOfFinitePresentation ιU ∧
        ∀ {T : Scheme.{0}} (t : T ⟶ Spec (CommRingCat.of R)) (ψU : T ⟶ ((U : X.Opens) : Scheme.{0}))
          (hψ : (ψU ≫ (U : X.Opens).ι) ≫ g = t),
          (Nonempty ((M.pullbackAlong (⟨ψU ≫ (U : X.Opens).ι, hψ⟩ : SchemeHomOver t g)).L ≅
              (RigidifiedLineBundle.unit (c := f) (ε := L.one (𝟙 (Spec (CommRingCat.of R)))) t).L) ↔
            ∃ ψ₀ : T ⟶ ZU, ψ₀ ≫ ιU = ψU)