=+Example 4.10 is somewhat similar, but there the o-field & is not countably generated and each set in it has probability either 0 or 1. In the present example 3 is countably generated and P(G) assumes every value between 0 and 1 as G ranges over . Example 4.10 is to some extent unnatural because the there is not countably generated. The present example, on the other hand, involves the pathological set H. This example is used in Section 33 in connection with conditional probability; see Problem 33.11.