Finite-temperature phase transition in a class of 4-state Potts   antiferromagnets
  We argue that the 4-state Potts antiferromagnet has a finite-temperature phase transition on any Eulerian plane triangulation in which one sublattice consists of vertices of degree 4. We furthermore predict the universality class of this transition. We then present transfer-matrix and Monte Carlo data confirming these predictions for the cases of the union-jack and bisected hexagonal lattices. 
Youjin Deng, Yuan Huang, Jesper Lykke Jacobsen, Jes\'us Salas, Alan D.   Sokal
cond-mat.stat-mech hep-lat math-ph math.MP