The Missing Ingredient in Zero-Shot Neural Machine Translation
Table 5: Average BLEU scores for multilingual model on IWSLT-2017; Zero-Shot results are marked (zs).
['[BOLD] Group', '[BOLD] vanilla direct', '[BOLD] vanilla pivot', '[BOLD] align(cosine) direct']
On this dataset, the baseline model does not seem to have trouble with decoding to the correct language and performs well on zero-shot translation from the start. This may be a symptom of this dataset being multi-way parallel with the English sentences shared across all language pairs. By training with the auxillary cosine alignment loss, we are once again able to match the quality of bridging.