Nikoletopoulos introduced long range order to this model by applying it to a small world graph.  
Nikoletopoulos introduced long range order to this model by applying it to a small world graph.  It can be used to model nucleation processes in the "critical droplets" theory, and general cases can be attacked by the Metropolis algorithm with a Boltzman distribution. Its three-dimensional form was proven to be computationally intractable by Istrail, and it was solved by Lars Onsager in the two dimensional case, where its critical value is two over the natural log of one plus the square root of two.  It is a specific case of the Potts model, and if the value of J in this model is negative, it results in the opposite of the effect usually associated with it.  It its most famous application it replaces intermolecular interactions with a grid of spins, which can only be up or down, and the energy is considered to be the sum of their interaction with each other and with an external magnetic field.  For 10 points, name this model of a ferromagnet.
Nikoletopoulos introduced long range order to this model by applying it to a small world graph.  
{Ising} Model