  Zero-lag synchronization (ZLS) is achieved in a very restricted mutually
coupled chaotic systems, where the delays of the self-coupling and the mutual
coupling are identical or fulfil some restricted ratios. Using a set of
multiple self-feedbacks we demonstrate both analytically and numerically that
ZLS is achieved for a wide range of mutual delays. It indicates that ZLS can be
achieved without the knowledge of the mutual distance between the communicating
partners and has an important implication in the possible use of ZLS in
communications networks as well as in the understanding of the emergence of
such synchronization in the neuronal activities.
