English
Closure distributes over pi: closure(pi I s) = pi I (closure(s_i)).
Русский
Замыкание распределяется над произведением: closure(pi I s) = pi I closure(s_i).
LaTeX
$$$$ closure(\\\\pi I s) = \\\\pi I (\\\\lambda i, closure(s_i)). $$$$
Lean4
theorem closure_pi_set {ι : Type*} {α : ι → Type*} [∀ i, TopologicalSpace (α i)] (I : Set ι) (s : ∀ i, Set (α i)) :
closure (pi I s) = pi I fun i => closure (s i) :=
Set.ext fun _ => mem_closure_pi