English
For q ∈ Polynomial R, x ∈ 𝕜 and s, the derivative within s of x ↦ aeval x q equals aeval x (derivative q).
Русский
Для q ∈ Polynomial R, x ∈ 𝕜 и s, производная внутри s от x ↦ aeval x q равна aeval x (derivative q).
LaTeX
$$$derivWithin\_\{\mathbb{K}\}\left(\lambda x, aeval x q\right) s x = aeval x (derivative q)$$$
Lean4
protected theorem derivWithin (hxs : UniqueDiffWithinAt 𝕜 s x) :
derivWithin (fun x => p.eval x) s x = p.derivative.eval x :=
by
rw [DifferentiableAt.derivWithin p.differentiableAt hxs]
exact p.deriv