books.google.se - There has in recent years been a remarkable growth of interest in the area of discrete integrable systems. Much progress has been made by applying symmetry groups to the study of differential equations, and connections have been made to other topics such as numerical methods, cellular automata and mathematical...http://books.google.se/books/about/Symmetries_and_Integrability_of_Differen.html?hl=sv&id=oi_jvhD1YU0C&utm_source=gb-gplus-shareSymmetries and Integrability of Difference Equations
