Module

RepresentsRelSubPic_nonempty_poincare_pullbackAlong_one_iso.lean

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

Triviality of the Poincare bundle pulled back along the identity section of the relative group law.

Declarations

AlgebraicGeometry.RelPicard.RepresentsRelSubPic.nonempty_poincare_pullbackAlong_one_iso
Source context 12 commands

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

section ProofImplementation
namespace JacobianVarieties.Picard.Proofs
namespace RepresentsRelSubPic_nonempty_poincare_pullbackAlong_one_iso
universe u
open _root_.CategoryTheory
open _root_.CategoryTheory.Limits
open _root_.CategoryTheory.MonoidalCategory
open _root_.AlgebraicGeometry
open _root_.AlgebraicGeometry.RelPicard
open _root_.NeronModelInfra
open _root_.GoodReductionJacobian
open scoped CategoryTheory.MonObj
theorem
    _root_.AlgebraicGeometry.RelPicard.RepresentsRelSubPic.nonempty_poincare_pullbackAlong_one_iso
    {R : Type u} [CommRing R] {C : Scheme.{u}} {c : C ⟶ Spec (CommRingCat.of R)}
    {ε : SchemeHomOver (𝟙 (Spec (CommRingCat.of R))) c}
    {P : SubPicGroupCondition c ε} {D : RelativePic0Designation R c}
    (h : RepresentsRelSubPic c ε P.toSubPicCondition D)
    (T : Over (Spec (CommRingCat.of R))) :
    let _ : GrpObj (Over.mk D.toBase) := h.grpObj
    Nonempty ((h.poincare.pullbackAlong
        ⟨(1 : T ⟶ Over.mk D.toBase).left, Over.w (1 : T ⟶ Over.mk D.toBase)⟩).L ≅
      (RigidifiedLineBundle.unit (c := c) (ε := ε) T.hom).L) := by
  intro groupObject
  let _ : CommGroup ((relSubPicPresheaf c ε P.toSubPicCondition).obj (Opposite.op T)) :=
    P.commGroupObj (Opposite.op T)
  have hone := congrArg Subtype.val (h.homEquiv_one T)
  exact Quotient.exact hone