(2007) proposed a Hastings sampler that specified an alternative rule probabilities θ H of a proposal distribution P (t i |w i , θ H ), where The rule probabilities θ H are based on the statistics collected from all other parse trees, and they are fixed for the conditional distribution of the current parse tree.
by using a variant of inside algorithm (Goodman, 1998), one can efficiently sample a parse tree, which will be either accepted or rejected based on the Metropolis choice.