Bethe ansatz at q=0 and periodic box-ball systems
  A class of periodic soliton cellular automata is introduced associated with crystals of non-exceptional quantum affine algebras. Based on the Bethe ansatz at q=0, we propose explicit formulas for the dynamical period and the size of certain orbits under the time evolution in A^{(1)}_n case. 
Atsuo Kuniba and Akira Takenouchi