forall C,B,C1,B1,.... in an algebra A, with C1 subset C2 .... with C=union(i=1,infinity,Ci) /\ B"=>"Ci forall i => B "=>" C proposition: algebra A a sigma algebra /\ P a probability charge on A representing "=>" => "=>" is monotone continuous <=> P is a probability measure (this induces finite additivity)