=+Prove by transfinite induction that (2.38) is in @ if the A ,, are, that every element of A has the form (2.38) for sets A ,, in ,, and that (2.31) holds with a in place of n. Define ( (w) = $ (I .,, I .,,... ), and show that B =[w.

w 4 (w)] lies in - for a < Q. Show that is strictly smaller than 3 for a n.