Word-Level Error Correction in Non-autoregressive Neural Machine Translation

Non-Autoregressive neural machine translation (NAT) not only achieves rapid training but also actualizes fast decoding. However, the implementation of parallel decoding is at the expense of quality. Due to the increase of speed, the dependence on the context of the target side is discarded which resulting in the loss of the translation contextual position perception ability. In this paper, we improve the model by adding capsule network layers to extract positional information more effectively and comprehensively, that is, relying on vector neurons to compensate for the defects of traditional scalar neurons to store the position information of a single segment. Besides, word-level error correction on the output of NAT model is used to optimize generated translation. Experiments show that our model is superior to the previous model, with a BLEU score of 26.12 on the WMT2014 En-De task and a BLEU score of 31.93 on the WMT16 Ro-En, and the speed is even more than six times faster than the autoregressive model.