Transfer learning approaches for Neural Machine Translation (NMT) train a NMT model on the assisting-target language pair (parent model) which is later fine-tuned for the source-target language pair of interest (child model), with the target language being the same. In many cases, the assisting language has a different word order from the source language. We show that divergent word order adversely limits the benefits from transfer learning when little to no parallel corpus between the source and target language is available. To bridge this divergence, We propose to pre-order the assisting language sentence to match the word order of the source language and train the parent model. Our experiments on many language pairs show that bridging the word order gap leads to significant improvement in the translation quality.

本研究针对神经机器翻译中的迁移学习方法展开研究，发现在源语言和目标语言间无或很少平行语料时，配合的语言与源语言词序差异会对迁移学习的效益产生负面影响。为了解决这种差异性，我们提出预先调整辅助语言句子的次序以便与源语言统一词序并对父级模型进行训练。实验表明，消除差异性对于提高翻译质量来说具有显著的改善作用。

针对极低资源语言的多语言神经机器翻译中的词序差异处理