Natural Computing is one of the most exciting developments in computer science, and there is a growing consensus that it will become a major field in computer science in this century. This series includes monographs, textbooks, and state-of-the-art collections covering the whole spectrum of Natural Computing and ranging from theory to applications. Series Editors: G. Rozenberg (Managing Editor), T. Bäck, A.E. Eiben, J.N. Kok, H.P. Spaink, Leiden Center for Natural Computing.