DYNAMICAL DEGREES OF FREEDOM OF DNA-SEQUENCES BY LOCAL AND GLOBAL SHORT-RANGE PREDICTION

The dynamical properties of DNA sequence samples have been analyzed on the basis of a procedure able to distinguish chaos from randomness. T he procedure relies on the concept of short-term (range) predictabilit y of low-dimensional chaotic motions and can distinguish merely linear stochastic processes, e.g. fractional Brownian motion, from truly non linear deterministic systems. The method consists in obtaining forecas ts on the basis of past events in the sequence. Two forecasting strate gies are used. The local strategy views the sequence as the outcome of a nonlinear process, whereas the global approach considers the series as the outcome of a linear stochastic process. For both approaches, t he predictive skill is computed and their inter-comparison allows us t o get insight into and an understanding of the structure of DNA sequen ces. Nucleotidic sequences belonging to different taxonomic and functi onal groups have been analyzed. Different behaviors have been detected according to the existence of finite correlation dimension for specif ic groups of sequences.