Neural Machine Translation with Explicit Phrase Alignment
Table 2: Comparison between the standard Transformer model and our latent variable model.
['model', 'MT06', 'MT08']
Our model is different from the standard model in two aspects. First, our model uses a phrase lattice to represent the search space. Second, empty phrases are introduced to make the search space more flexible than that of conventional SMT. We find that our model slightly improves over the standard model, suggesting that we can use the phrase-based search space to replace the standard search space for lexically and structurally constrained decoding.