Module

RigidifiedLineBundle_nonempty_iso_unit_pullback_rigSection_of_squareZero_of_pullback_iso.lean

Nyll.JacobianVarieties.Picard.RigidifiedLineBundle_nonempty_iso_unit_pullback_rigSection_of_squareZero_of_pullback_iso
1 declaration indexed from sourceView source ↗

Relative Picard varieties and fibre cohomology

Construct a unit isomorphism of rigidified line bundles over a square-zero thickening from the given pullback isomorphism.

Declarations

AlgebraicGeometry.RelPicard.RigidifiedLineBundle.nonempty_iso_unit_pullback_rigSection_of_squareZero_of_pullback_iso
Source context 8 commands

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

section ProofImplementation
namespace JacobianVarieties.Picard.Proofs
namespace RigidifiedLineBundle_nonempty_iso_unit_pullback_rigSection_of_squareZero_of_pullback_iso
attribute [-simp] AlgebraicGeometry.tilde.functorCompPullbackSpecIso_app
universe u
open CategoryTheory CategoryTheory.Limits AlgebraicGeometry AlgebraicGeometry.RelPicard
  NeronModelInfra TensorProduct
open RigidifiedLineBundle_nonempty_iso_unit_pullback_rigSection_of_squareZero_of_pullback_iso in
with_weak_namespace _root_.AlgebraicGeometry.RelPicard.RigidifiedLineBundle
theorem nonempty_iso_unit_pullback_rigSection_of_squareZero_of_pullback_iso
    {R : Type u} [CommRing R] {C : Scheme.{u}} (c : C ⟶ Spec (CommRingCat.of R))
    (ε : SchemeHomOver (𝟙 (Spec (CommRingCat.of R))) c)
    {B : Type u} [CommRing B] [Algebra R B] (I : Ideal B) (hI : I ^ 2 = ⊥)
    (ι : SchemeHomOver
      (Spec.map (CommRingCat.ofHom (algebraMap R (B ⧸ I))))
      (Spec.map (CommRingCat.ofHom (algebraMap R B))))
    (hι : ι.1 = Spec.map (CommRingCat.ofHom (Ideal.Quotient.mk I)))
    (M : RigidifiedLineBundle c ε (Spec.map (CommRingCat.ofHom (algebraMap R (B ⧸ I)))))
    (L' : (pullback c (Spec.map (CommRingCat.ofHom (algebraMap R B)))).Modules)
    (hL' : Scheme.Modules.IsInvertible L')
    (isoL : Nonempty ((Scheme.Modules.pullback (baseChangeSnd c ι)).obj L' ≅ M.L)) :
    Nonempty
      ((Scheme.Modules.pullback (rigSection c (Spec.map (CommRingCat.ofHom
        (algebraMap R B))) ε)).obj L'
        ≅ SheafOfModules.unit (Spec (CommRingCat.of B)).ringCatSheaf)