Deformations of Dynamics Associated to the Chiral Potts Model
  We describe deformations of non-linear (birational) representations of discrete groups generated by involutions, having their origin in the theory of the symmetric five-state Potts model. One of the deformation parameters can be seen as the number $q$ of states of a chiral Potts models. This analogy becomes exact when $q$ is a Fermat number. We analyze the stability of the corresponding dynamics, with a particular attention to orbits of finite order. 
M.P. Bellon, J-M. Maillard, G. Rollet, C-M. Viallet