English
If f is differentiable, then all iterates f^[n] are differentiable for every n.
Русский
Если f дифференцируема, то все итерации f^[n] дифференцируемы для каждого n.
LaTeX
$$$$ \\text{Differentiable}_{\\mathbb{K}} f \\;\to\ \forall n \\in \\mathbb{N},\; \\text{Differentiable}_{\\mathbb{K}} (f^{[n]}). $$$$
Lean4
@[fun_prop]
theorem comp {g : F → G} (hg : Differentiable 𝕜 g) (hf : Differentiable 𝕜 f) : Differentiable 𝕜 (g ∘ f) := fun x =>
DifferentiableAt.comp x (hg (f x)) (hf x)