The chiral Potts model is a spin model on a planar lattice in statistical mechanics studied by Helen Au-Yang Perk and Jacques Perk, among others. It may be viewed as a generalization of the Potts model, and as with the Potts model, the model is defined by configurations which are assignments of spins to each vertex of a graph, where each spin can take one of N values. To each edge joining vertices with assigned spins n and n ′ , a Boltzmann weight W ( n , n ′ ) is assigned. For this model, chiral means that W ( n , n ′ ) ≠ ≠ W ( n ′ , n ) . When the weights satisfy the Yang–Baxter equation, it is integrable, in the sense that certain quantities can be exactly evaluated.