Mesocopic comparison of complex networks based on periodic orbits.

Complex noiseless dynamical systems can be represented in a compressed manner by unstable periodic orbits. It is unknown, however, how to use this technique to obtain a suitable notion of similarity among them, how to extend such an approach to more general complex networks, and how to apply such a method in the important case of noisy systems. Our approach provides a solution to these questions. For a proof-of-concept, we consider Drosophila's precopulatory courtship, where our method reveals the existence of a complex grammar (similar to those found in complex physical systems and in language), leading to the conclusion that the observed grammar is very unlikely the product of chance.