Proposition 7.3.14: Monotone Sequences of Measurable Sets
If { An } is a sequence of measurable sets
that is decreasing, i.e.
Aj
Aj+1
for all j, and m(A1) is
finite, then
Aj
for all j, then

lim m(Aj) = m(If { An } is a sequence of measurable sets that is increasing in the sense that Aj+1Aj)

lim m(Aj) = m(Aj)