Towards Robust Neural Machine Translation
Table 5: Translation results of synthetic perturbations on the validation set in Chinese-English translation. “1 Op.” denotes that we conduct one operation (swap, replacement or deletion) on the original sentence.
['Synthetic Type', 'Training', '0 Op.', '1 Op.', '2 Op.', '3 Op.', '4 Op.', '5 Op.']
This means that our approaches have the capability of resisting perturbations. Along with the number of operations increasing, the performance on MLE drops quickly. Although the performance of our approaches also drops, we can see that our approaches consistently surpass MLE. In ASTlexical, with 0 operation, the difference is +2.19 (43.57 Vs. 41.38) for all synthetic types, but the differences are enlarged to +3.20, +9.39, and +3.12 respectively for the three types with 5 operations.