Chaotic-like behaviour in chains of stable nonlinear oscillators

Irregular evolution is observed in a chain of forced Duffing oscillators even when the maximum Lyapunov exponent is strictly negative. This phenomenon generalizes similar results previously obtained in the context of coupled-map lattices. The relationship with chaotic cellular automata is investigated by introducing a suitable encoding: while in some parameter region the evolution of the chain of oscillators turns out to be described exactly by a deterministic cellular automaton with a finite interaction range, in other regions even automata with an infinite range are unable to reproduce the observed patterns. We discuss the possible connection with an information downgrade occurring during the observation process.