
theorem
for X be non empty set, S be SigmaField of X, M be sigma_Measure of S
 holds
  M is sigma_finite
iff
  ex F be Set_Sequence of S st
    F is non-descending & (for n be Nat holds M.(F.n) < +infty)
  & lim F = X by LM0902a,LM0902b;
