Beyond Error Propagation in Neural Machine Translation: Characteristics of Language Also Matter
Table 7: Number of dependencies in left and right half of English (De-En) and Japanese (En-Jp) training corpus. The number varies a lot since the two training corpus have different training sentences.
['[EMPTY]', '[BOLD] English', '[BOLD] Japanese']
As can be observed, for English sentences, the left-half words depend more on each other than the right-half words, while for the Japanese sentences, the right-half words have more dependencies. This observation is consistent with our observations on accuracy drop, and can well explain the high accuracy of left part in English translation and right part in Japanese translation.