English
In the localization equivalence setup, the counit component at L₂.obj X is described via a specified isomorphism and the β component.
Русский
В рамках локализационной эквивалентности компонент counit при L₂.obj X описывается через заданный изоморфизм и компонент β.
LaTeX
$$$\big(\text{equivalence } L_1 W_1 L_2 W_2 G G' F F' \alpha \beta\big).\mathrm counitIso.app (L_2.obj X) = (\text{Lifting.iso } L_2 W_2 (F \circ G') (F' \circ G')).app X \;\;\Rightarrow\; \beta.app X$$$
Lean4
@[simp]
theorem equivalence_counitIso_app (X : C₂) :
(equivalence L₁ W₁ L₂ W₂ G G' F F' α β).counitIso.app (L₂.obj X) =
(Lifting.iso L₂ W₂ (F ⋙ G') (F' ⋙ G')).app X ≪≫ β.app X :=
by
ext
dsimp [equivalence, Equivalence.mk]
rw [liftNatTrans_app]
dsimp [Lifting.iso]
rw [comp_id]