Another algebraic variational principle for the spectral curve of matrix   models
  We propose an alternative variational principle whose critical point is the algebraic plane curve associated to a matrix model (the spectral curve, i.e. the large $N$ limit of the resolvent). More generally, we consider a variational principle that is equivalent to the problem of finding a plane curve with given asymptotics and given cycle integrals. This variational principle is not given by extremization of the energy, but by the extremization of an "entropy". 
B. Eynard (IPHT CEA Saclay, CRM)
hep-th math-ph math.MP