English
Disjointness with a supremum is equivalent to disjointness with each component: Disjoint (⨆ i, f i) a ⇔ ∀ i, Disjoint (f i) a.
Русский
Свойство несовместности с sup эквивалентно несовместности с каждой компонентой: Disjoint (⨆ i, f i) a ⇔ ∀ i, Disjoint (f i) a.
LaTeX
$$$\\operatorname{Disjoint}\\Bigl( \\bigvee_i f(i), a \\Bigr) \\quad\\Leftrightarrow\\quad \\forall i, \\operatorname{Disjoint}(f(i), a)$$$
Lean4
theorem iSup_disjoint_iff {f : ι → α} : Disjoint (⨆ i, f i) a ↔ ∀ i, Disjoint (f i) a := by
simp only [disjoint_iff, iSup_inf_eq, iSup_eq_bot]