The formula of our model is the same as <cite>Ninomiya et al. (2006)</cite><cite>'s model 3</cite>. But, <cite>their model</cite> is not a probabilistic model with a reference distribution. Both our model and <cite>their model</cite> consist of the probabilities for lexical entries (= p model1 (T |w)) and the probabilities for phrase structures (= the rest of each formula). The only difference between our model and <cite>their model</cite> is the way of how to train model parameters for phrase structures.