Examples 7.3.7(d): Measurable Sets
Suppose A and B are measurable. Then comp(A) and comp(B) are also measurable, and because of the previous exercise the set comp(A) comp(B) is measurable.But since
comp(A) comp(B) = comp(A B)the set comp(A B) is measurable. Finally, the complement of that set must be measurable, which is what we wanted to prove.