It is shown that the consistency strength of ZF + DC + "the closed unbounded
ultrafilter on omega_1 is an ultrafilter" is exactly ZFC + one measurable
cardinal.Comment: I apologize for the fact that this is not ready for publication. I've
gone back to revise it several times, and each time got distracted by
something new. I've decided that it is better to at least make it available
in its current for