  Let D = { d_n } be a countable collection of Delta^1_3 degrees. Assuming that
all co-analytic games on integers are determined (or equivalently that all
reals have ``sharps''), we prove that either D has a Delta^1_3-minimal upper
bound, or that for any n, and for every real r recursive in d_n, games in the
pointclasses Delta^1_2(r) are determined. This is proven using Core Model
theory.
