English
For any f, g, s, the principal-inf relation yields (f ⊔ g) bind h equals (f bind h) ⊔ (g bind h).
Русский
Для любых f, g и s, отношение principal-inf даёт: bind от (f ⊔ g) к h равен объединению bind f h и bind g h.
LaTeX
$$$(f \\sqcup g) \\!\\mathrm{bind}\\ h = (f \\mathrm{bind}\\ h) \\sqcup (g \\mathrm{bind}\\ h)$$$
Lean4
theorem bind_le {f : Filter α} {g : α → Filter β} {l : Filter β} (h : ∀ᶠ x in f, g x ≤ l) : f.bind g ≤ l :=
join_le <| eventually_map.2 h