Poincaré recurrences and multifractal properties of genomic sequences

We propose the return times spectra as a tool to analyze the genomic sequences. The spectra discriminate between regular, chaotic and mixed dynamical systems since generally their decay follows, respectively, an exponential law, a power law or is a linear combination of them. The analysis of words of n bases from a DNA sequence exhibits the same exponential behavior for the coding and noncoding component. The multifractal analysis shows a definite difference, which suggests a less uniform structure for the noncoding part.