English
If f is differentiable within s, then x ↦ f(x)^c is differentiable within s for fixed c if f(x) ∈ slitPlane.
Русский
Если f дифференцируема внутри s, то x ↦ f(x)^c дифференцируема внутри s для фиксированного c при условии f(x) ∈ slitPlane.
LaTeX
$$$\\\\forall f, s, x, c, DifferentiableWithinAt \\mathbb{C} f s x \\\\Rightarrow DifferentiableWithinAt \\mathbb{C} (\\\\lambda x, f(x)^c) s x$$$
Lean4
@[fun_prop]
theorem cpow_const (hf : DifferentiableWithinAt ℂ f s x) (h0 : f x ∈ slitPlane) :
DifferentiableWithinAt ℂ (fun x => f x ^ c) s x :=
hf.cpow (differentiableWithinAt_const c) h0