We use a method suggested by Kolmogorov complexity to examine some relations between Kolmogorov complexity and noncomputability. In particular we show that the method consistently gives us more information than conventional ways of demonstrating noncomputability . Also, many sets which are awkward to embed into the halting problem are easily shown noncomputable. We also prove a gap-theorem for outputting consecutive integers and find, for a given length n, a statement of length n with maximal proof length.

Let ω be a Kolmogorov–Chaitin random sequence with ω1: n denoting the first n digits of ω. Let P be a recursive predicate defined on all finite binary strings such that the Lebesgue measure of the set {ω|∃nP(ω1: n )} is a computable real α. Roughly, P holds with computable probability for a random infinite sequence. Then there is an algorithm which on input indices for any such P and α finds an n such that P holds within the first (...) n digits of ω or not in ω at all. We apply the result to the halting probability Ω and show that various generalizations of the result fail. (shrink)