Extracting Kolmogorov Complexity with Applications to Dimension Zero-One Laws

Lance Fortnow, John M. Hitchcock, A. Pavan,
N. V. Vinodchandran, and Fengming Wang

We apply results on extracting randomness from independent sources to "extract" Kolmogorov complexity. For any α, ε > 0, given a string x with K(x) > α|x|, we show how to use a constant number of advice bits to efficiently compute another string y, |y|=Ω(|x|), with K(y) > (1-ε)|y|. This result holds for both unbounded and space-bounded Kolmogorov complexity.

We use the extraction procedure for space-bounded complexity to establish zero-one laws for the strong dimension of complexity classes within ESPACE. For example, Dim(E | ESPACE) is either 0 or 1.

The extraction procedure for unbounded complexity yields a similar result for constructive strong dimension: for any sequence S with Dim(S) > 0, there is a sequence TT S with Dim(T) arbitrarily close to 1.