your counter example is not true if b = anything greater than or equal to omega, like it has to be, by the hypothesis.
The hypothesis says that one or both of the ordinals is greater than or equal to omega, and if one is not greater than omega then it can't be less than two.
thanks.
clic-clac: thanks for the hint, but i'm struggling with what the mapping would go to. In other words,
so i show by induction that a^n = a (for a > omega), for n < b < omega. Then i feel like the next step has to be to show a map from U a^n ---> something, but i feel like this map can't just be to omega. does it have to be to omega x omega, or a x omega, or...?
Thanks, and sorry if this is muddled.