Vincent Beffara, Hugo Duminil-Copin. The self-dual point of the two-dimensional random-cluster model is critical for $q\geq 1$.
Probability Theory and Related Fields, Springer Verlag, 2012, 153 (3-4), pp.511 - 542.
⟨10.1007/s00440-011-0353-8⟩.
⟨ensl-00495872⟩