English
If a coalgebra morphism f: A → B has an isomorphism carrier f.f in C, then f is an isomorphism in Coalgebra G.
Русский
Если морфизм коалгебр f: A → B имеет изоморфную carrier-часть f.f в C, то f является изоморфизмом в G-коалгебрах.
LaTeX
$$$\\\\forall A,B \\in G. Coalgebra, \\\\forall f: A \\\\to B, [IsIso f.f] \\\\Rightarrow IsIso f.$$$
Lean4
/-- Given a coalgebra morphism whose carrier part is an isomorphism, we get a coalgebra isomorphism.
-/
theorem coalgebra_iso_of_iso {A B : Coalgebra G} (f : A ⟶ B) [IsIso f.f] : IsIso f :=
⟨⟨{ f := inv f.f
h := by
rw [IsIso.eq_inv_comp f.f, ← f.h_assoc]
simp },
by cat_disch⟩⟩