On Stochastic Estimation of Partition Function

In this paper, we show analytically that the duality of normal factor graphs (NFG) can facilitate stochastic estimation of partition functions. In particular, our analysis suggests that for the q−ary two-dimensional nearest-neighbor Potts model, sampling from the primal NFG of the model and sampling from its dual exhibit opposite behaviours with respect to the temperature of the model. For high-temperature models, sampling from the primal NFG gives rise to better estimators whereas for lowtemperature models, sampling from the dual gives rise to better estimators. This analysis is validated by experiments.