English
If X i are spaces and i indexes, the map p ↦ p i from the product to X i is ContinuousOn for any fixed i.
Русский
Для фиксированного i отображение p ↦ p(i) из произведения в X_i непрерывно на s.
LaTeX
$$$$\text{ContinuousOn}(p \mapsto p(i))\ s.$$$$
Lean4
@[fun_prop]
theorem continuousOn_apply {ι : Type*} {X : ι → Type*} [∀ i, TopologicalSpace (X i)] (i : ι) (s) :
ContinuousOn (fun p : ∀ i, X i => p i) s :=
Continuous.continuousOn (continuous_apply i)