English
Let a be a function a: ι → α i. Then the top-interval structure on the product is given by coordinatewise Ici, i.e., the set {x : ∀ i, α i | a(i) ≤ x(i)} is described coordinatewise.
Русский
Пусть a: ι → α i. Тогда структура верхних интервалов на произведении задаётся координатно через Ici: множество {x | a(i) ≤ x(i)} по координатам.
LaTeX
$$$$ \\text{Ici}\\bigl(a\bigr) = \\prod_i \\text{Ici}\\bigl(a_i\\bigr) $$$$
Lean4
instance instLocallyFiniteOrderTop : LocallyFiniteOrderTop (∀ i, α i) :=
LocallyFiniteOrderTop.ofIci _ (fun a => piFinset fun i => Ici (a i)) fun a x => by
simp_rw [mem_piFinset, mem_Ici, le_def]