7In training, our goal is to find a set of source-totarget model parameters that minimizes the training objective: With learned source-to-target model parameterŝ θ x→y , we use the standard decision rule as shown in Equation 1to find the translationŷ for a source sentence x.
a major difficulty faced by our approach is the intractability in calculating the gradients because of the exponential search space of target sentences.