English
Variant: HasDerivAtFilter (λ x, Fin.cons (φ x) (φs x)) (Fin.cons φ' φs') x iff HasDerivAtFilter φ φ' x ∧ HasDerivAtFilter φs φs' x.
Русский
Вариант: HasDerivAtFilter от Fin.cons равно произведению производных частей.
LaTeX
$$$HasDerivAtFilter (\lambda x, Fin.cons (φ x) (φs x)) (Fin.cons φ' φs') x \iff HasDerivAtFilter φ φ' x ∧ HasDerivAtFilter φs φs' x$$$
Lean4
theorem finCons {φ' : F' 0} {φs' : Π i, F' (Fin.succ i)} {l : Filter 𝕜} (h : HasDerivAtFilter φ φ' x l)
(hs : HasDerivAtFilter φs φs' x l) : HasDerivAtFilter (fun x => Fin.cons (φ x) (φs x)) (Fin.cons φ' φs') x l :=
hasDerivAtFilter_finCons'.mpr ⟨h, hs⟩