  However, the phenomenon of complexity oscillation does not pose as significant a problem for prefix-free Kolmogorov complexity. Complexity oscillation does arise, but in fact the inefficiency of prefix-free encodings is a benefit here: ‘\(K\) exceeds \(C\) by so much that the complexity of the prefix does not drop below the length of the prefix itself (for random infinite \(\omega)\)’ (Li and Vitányi 2008: 221). That is, while the complexity of some initial segments dips down, it always remains greater than the length of the prefix. So it can be that, uniformly, when \(x\) is an infinite sequence, for any of its initial subsequences \(\sigma , K(\sigma) \ge  \lvert\sigma\rvert\). This suggests that we can extend prefix-free Kolmogorov complexity to the infinite case in the straightforward way: an infinite sequence \(x\) is prefix-free Kolmogorov random iff every finite initial subsequence is prefix-free Kolmogorov random.