Approximating the partition function of the ferromagnetic Potts model

  • Authors:
  • Leslie Ann Goldberg;Mark Jerrum

  • Affiliations:
  • University of Liverpool, United Kingdom;Queen Mary, University of London, United Kingdom

  • Venue:
  • Journal of the ACM (JACM)
  • Year:
  • 2012

Quantified Score

Hi-index 0.01

Visualization

Abstract

We provide evidence that it is computationally difficult to approximate the partition function of the ferromagnetic q-state Potts model when q 2. Specifically, we show that the partition function is hard for the complexity class #RHPi under approximation-preserving reducibility. Thus, it is as hard to approximate the partition function as it is to find approximate solutions to a wide range of counting problems, including that of determining the number of independent sets in a bipartite graph. Our proof exploits the first-order phase transition of the “random cluster” model, which is a probability distribution on graphs that is closely related to the q-state Potts model.