English
If x is not in the atom of y, then the atoms are disjoint.
Русский
Если x не принадлежит атому y, атомы x и y несовместны.
LaTeX
$$$$ x \notin \operatorname{measurableAtom}(y) \Rightarrow \operatorname{measurableAtom}(x) \cap \operatorname{measurableAtom}(y) = \emptyset $$$$
Lean4
theorem disjoint_measurableAtom_of_notMem {x y : β} (hx : x ∉ measurableAtom y) :
Disjoint (measurableAtom x) (measurableAtom y) :=
by
rw [Set.disjoint_iff_inter_eq_empty]
ext z
simp only [mem_inter_iff, mem_empty_iff_false, iff_false, not_and]
intro hzx hzy
have h1 := measurableAtom_eq_of_mem hzx
have h2 := measurableAtom_eq_of_mem hzy
rw [← h2, h1] at hx
exact hx (mem_measurableAtom_self x)