English
Variant: HasDerivWithinAt (λ x, Fin.cons (φ x) (φs x)) (Fin.cons φ' φs') s x iff both HasDerivWithinAt φ φ' s x and HasDerivWithinAt φs φs' s x.
Русский
Вариант: HasDerivWithinAt для Fin.cons распадается на производные частей.
LaTeX
$$$HasDerivWithinAt (\lambda x, Fin.cons (φ x) (φs x)) (Fin.cons φ' φs') s x \iff HasDerivWithinAt φ φ' s x ∧ HasDerivWithinAt φs φs' s x$$$
Lean4
theorem hasDerivWithinAt_finCons {φ' : Π i, F' i} :
HasDerivWithinAt (fun x => Fin.cons (φ x) (φs x)) φ' s x ↔
HasDerivWithinAt φ (φ' 0) s x ∧ HasDerivWithinAt φs (fun i => φ' i.succ) s x :=
hasDerivAtFilter_finCons