=+P(C) = 0. Show that + is a o-field. For such a set A define P+ (A) = P(B).

Show that the definition is consistent, that P+ is a probability measure on $ +, and that (n), F+, P+) is complete. Show that, if (0, 91, P1) is any complete extension of (0, 9, P), then F+c $, and P, agrees with Pt on F";