Counting the Changes of Random ∆2 Sets

Consider a Martin-Löf random ∆2 set Z. We give lower bounds for the number of changes of Zs n for computable approximations of Z. We show that each nonempty Π 1 class has a low member Z with a computable approximation that changes only o(2) times. We prove that each superlow ML-random set already satisfies a stronger randomness notion called balanced randomness, which implies that for each computable approximation and each constant c, there are infinitely many n such that Zs n changes more than c2 times.