Evaluating Robustness to Input Perturbationsfor Neural Machine Translation
Table 4: BLEU scores of using different subword segmentation methods on two datasets with natural noise. Subword regularization methods do not achieve consistent improvement over BPE, nor with or without fine-tuning.
['[EMPTY]', 'Model', 'MTNT (mtnt2019) EN→JA', 'MTNT (mtnt2019) JA→EN', 'MTNT (mtnt2019) EN→FR', 'MTNT (mtnt2019) FR→EN', '4SQ FR→EN']
The training data we use may already cover common natural misspellings, perhaps contributing to the failure of regularization methods to improve over BPE in this case.