English
A simple extensional lemma for morphisms between SingleFunctors: equality of morphisms implies equality of the objects.
Русский
Элементарная лема экстенсивности для морфизмов между SingleFunctors: равенство морфизмов => равенство объектов.
LaTeX
$$$$ \\text{[simp]}\\; \\text{hom\_ext} \\; (f,g: F \\to G) (h: f.hom = g.hom) \\Rightarrow f = g $$$$
Lean4
theorem shiftIso_add'_hom_app (n m mn : A) (hnm : m + n = mn) (a a' a'' : A) (ha' : n + a = a') (ha'' : m + a' = a'')
(X : C) :
(F.shiftIso mn a a'' (by rw [← hnm, ← ha'', ← ha', add_assoc])).hom.app X =
(shiftFunctorAdd' D m n mn hnm).hom.app ((F.functor a'').obj X) ≫
((F.shiftIso m a' a'' ha'').hom.app X)⟦n⟧' ≫ (F.shiftIso n a a' ha').hom.app X :=
by simp [F.shiftIso_add' n m mn hnm a a' a'' ha' ha'']