Resonance and web structure in discrete soliton systems: the   two-dimensional Toda lattice and its fully discrete and ultra-discrete   versions
  We present a class of solutions of the two-dimensional Toda lattice equation, its fully discrete analogue and its ultra-discrete limit. These solutions demonstrate the existence of soliton resonance and web-like structure in discrete integrable systems such as differential-difference equations, difference equations and cellular automata (ultra-discrete equations). 
Ken-ichi Maruno and Gino Biondini