Let ( = {1, 2,...}, and for any A ( (, let a = sup A. On the discrete Ï-field, define μo by Then (i)

Let ( = {1, 2,...}, and for any A ( (, let a = sup A. On the discrete σ-field, define μo by

Then
(i) Show that μo is an outer measure.
(ii) Determine the class Ao of μo-measureable sets.

if A is finite, a 1 if A is infinite.