  This dip in complexity of an initial subsequence will occur infinitely often in even a random infinite sequence, a phenomenon known as complexity oscillation (Li and Vitányi 2008: §2.5.1). This phenomenon means that ‘it is difficult to express a universal sequential test precisely in terms of \(C\)-complexity’ (Li and Vitányi 2008: 151), and the best that can be precisely done is to find upper and lower bounds expressible in terms of ordinary Kolmogorov complexity between which the set of ML-random sequences falls (Li and Vitányi 2008: § 2.5.3). 