Another example of higher order randomness

Abstract

We consider the notion of algorithmic randomness relative to an oracle. We prove that the probability β that a program for infinite computations (a program that never halts) outputs a cofinite set is random in the second jump of the halting problem. Indeed, we prove that β is exactly as random as the halting probability of a universal machine equipped with an oracle for the second jump of the halting problem, in spite of the fact that β is defined without considering oracles.