English
The equivalence between preservesSheafification and isIso of the sheafComposeNatTrans holds under HasSheafCompose assumptions.
Русский
Эквивалентность сохраняет шарообразование и изоморфизм SheafComposeNatTrans сохраняется при наличии HasSheafCompose.
LaTeX
$$$J.PreservesSheafification F \iff IsIso (\text{sheafComposeNatTrans } J F adj_1 adj_2)$$$
Lean4
theorem sheafComposeNatTrans_app_uniq (P : Cᵒᵖ ⥤ A) (α : G₂.obj (P ⋙ F) ⟶ (sheafCompose J F).obj (G₁.obj P))
(hα : adj₂.unit.app (P ⋙ F) ≫ (sheafToPresheaf J B).map α = whiskerRight (adj₁.unit.app P) F) :
α = (sheafComposeNatTrans J F adj₁ adj₂).app P :=
by
apply (adj₂.homEquiv _ _).injective
dsimp [sheafComposeNatTrans]
erw [Equiv.apply_symm_apply]
rw [← hα]
apply adj₂.homEquiv_unit