The Hintermann-Merlini-Baxter-Wu and the Infinite-Coupling-Limit   Ashkin-Teller Models
  We show how the Hintermann-Merlini-Baxter-Wu model (which is a generalization of the well-known Baxter-Wu model to a general Eulerian triangulation) can be mapped onto a particular infinite-coupling-limit of the Ashkin-Teller model. We work out some mappings among these models, also including the standard and mixed Ashkin-Teller models. Finally, we compute the phase diagram of the infinite-coupling-limit Ashkin-Teller model on the square, triangular, hexagonal, and kagome lattices. 
Yuan Huang, Youjin Deng, Jesper Lykke Jacobsen, and Jesus Salas
cond-mat.stat-mech hep-lat