Module

SheafPullbackGerms.lean

Nyll.SchemeTheory.Topology.SheafPullbackGerms
1 declaration indexed from sourceView source ↗

Germs and the actual inverse-image adjunction

The stalk comparison for the chosen sheaf pullback intertwines germs with the unit of its actual pullback-pushforward adjunction.

The Lean proofs are original.

Declarations

SchemeTheory.germ_sheafStalkPullbackIso_hom

Taking a germ after restriction along a continuous map is the same as applying the canonical comparison to the original germ.

Source context 5 commands

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

noncomputable section
universe u
open CategoryTheory TopologicalSpace Opposite
namespace SchemeTheory
variable {X Y : TopCat.{u}}
theorem germ_sheafStalkPullbackIso_hom (f : X ⟶ Y)
    (F : CategoryTheory.Sheaf (Opens.grothendieckTopology Y) (Type u))
    (x : X) (U : Opens Y) (hx : f x ∈ U) :
    TopCat.Presheaf.germ F.obj U (f x) hx ≫ (sheafStalkPullbackIso f F x).hom =
      (((TopCat.Sheaf.pullbackPushforwardAdjunction (Type u) f).unit.app F).hom.app
        (op U)) ≫
      TopCat.Presheaf.germ ((TopCat.Sheaf.pullback (Type u) f).obj F).obj
        ((Opens.map f).obj U) x hx