On uniqueness of the q-state Potts model on a self-dual family of graphs

Jean-Michel Billiot (1) , Franck Corset (1) , Eric Fontenas (1)

1 SAGAG - Statistique Appliquée et de Géométrie Aléatoire de Grenoble

This paper deals with the location of the complex zeros of the Tutte polynomial for a class of self-dual graphs. For this class of graphs, as the form of the eigenvalues is known, the regions of the complex plane can be focused on the sets where there is only one dominant eigenvalue in particular containing the positive half plane. Thus, in these regions, the analyticity of the pressure can be derived easily. Next, some examples of graphs with their Tutte polynomial having a few number of eigenvalues are given. The cases of the strip of triangles with a double edge, the wheel and the cycle with an edge having a high order of multiplicity are presented. In particular, for this last example, we remark that the well known conjecture of Chen et al. is false in the finite case.

Mots clés: Tutte polynomial; q-Potts model; Self-dual graph; Analytic function

Domaines: Combinatoire [math.CO]

Jean-Michel Billiot, Franck Corset, Eric Fontenas. On uniqueness of the q-state Potts model on a self-dual family of graphs. Journal of Statistical Physics, 2010, 139 (6), pp.960-971. ⟨10.1007/s10955-010-9977-9⟩. ⟨hal-00385063⟩