Foundations on Natural and Artificial Computation : 4th International Work-conference on the Interplay Between Natural and Artificial Computation, IWINAC 2011, La Palma, Canary Islands, Spain, May 30 - June 3, 2011. Proceedings, Part I - José Manuel Ferrández, José Ramón Álvarez Sánchez, Félix Paz, F. Javier Toledo ((Lecture Notes in Computer Science))