English
For any f: α → G and any x ∈ α, and z ∈ ℤ, the map a ↦ a^z is continuous at x whenever f is continuous at x.
Русский
Для любого f: α → G, точки x и z ∈ ℤ, отображение a ↦ a^z непрерывно в x, если f непрерывна в x.
LaTeX
$$$\forall f:\alpha \to G, \forall x:\alpha, \forall z:\mathbb{Z}, \text{ContinuousAt}(a\mapsto a^{z}, x).$$$
Lean4
@[to_additive (attr := fun_prop)]
theorem zpow {f : α → G} {x : α} (hf : ContinuousAt f x) (z : ℤ) : ContinuousAt (fun x => f x ^ z) x :=
Filter.Tendsto.zpow hf z