Module

InverseLimitStageCoherence.lean

Nyll.EtaleFundamentalGroups.FiniteEtale.InverseLimitStageCoherence
2 declarations indexed from sourceView source ↗

Coherence of the actual stage cocone

The cartesian stage transitions respect the canonical identity and composition isomorphisms of pullback. Applying the localization functor therefore gives the actual coherent cocone used in its 2-colimit presentation.

Declarations

AlgebraicGeometry.FiniteEtale.InverseLimitModel.transition_comp_app

The two successive cartesian transitions agree with the transition of the composite after the canonical pullback-composition comparison.

Source context 6 commands

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

noncomputable section
open CategoryTheory
namespace AlgebraicGeometry.FiniteEtale.InverseLimitModel
universe u v w
attribute [local instance] finiteEtaleOverCategoryCoherence
  finiteEtaleHasPullbacksAlongCoherence finiteEtaleStableUnderBaseChangeAlongCoherence
variable {J : Type v} [Category.{w} J] (F : J ⥤ Scheme.{u})
theorem transition_comp_app {i j k : J} (a : i ⟶ j) (b : j ⟶ k)
    (A : FiniteEtale (F.obj k)) :
    (stageInclusion F i).map
        ((MorphismProperty.Over.pullbackComp
          (P := @IsFiniteEtale) (Q := ⊤)
          (F.map a) (F.map b) (F.map (a ≫ b)) (F.map_comp a b)).hom.app A) ≫
      (transition F a).app ((pullback (F.map b)).obj A) ≫
      (transition F b).app A = (transition F (a ≫ b)).app A
AlgebraicGeometry.FiniteEtale.InverseLimitModel.transition_id_app

The cartesian transition over an identity is the actual pullback identity comparison, including the diagram's map-id equality.

Source context 6 commands

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

noncomputable section
open CategoryTheory
namespace AlgebraicGeometry.FiniteEtale.InverseLimitModel
universe u v w
attribute [local instance] finiteEtaleOverCategoryCoherence
  finiteEtaleHasPullbacksAlongCoherence finiteEtaleStableUnderBaseChangeAlongCoherence
variable {J : Type v} [Category.{w} J] (F : J ⥤ Scheme.{u})
theorem transition_id_app (i : J) (A : FiniteEtale (F.obj i)) :
    (transition F (𝟙 i)).app A =
      (stageInclusion F i).map
        ((MorphismProperty.Over.pullbackCongr
            (P := @IsFiniteEtale) (Q := ⊤) (F.map_id i) ≪≫
          pullbackIdIso (F.obj i)).hom.app A)