The advent of deep learning has led to a significant gain in machine translation. However, most of the studies required a large parallel dataset which is scarce and expensive to construct and even unavailable for some languages. This paper presents a simple yet effective method to tackle this problem for low-resource languages by augmenting high-quality sentence pairs and training NMT models in a semi-supervised manner. Specifically, our approach combines the cross-entropy loss for supervised learning with KL Divergence for unsupervised fashion given pseudo and augmented target sentences derived from the model. We also introduce a SentenceBERT-based filter to enhance the quality of augmenting data by retaining semantically similar sentence pairs. Experimental results show that our approach significantly improves NMT baselines, especially on low-resource datasets with 0.46--2.03 BLEU scores. We also demonstrate that using unsupervised training for augmented data is more efficient than reusing the ground-truth target sentences for supervised learning.

本文介绍一种半监督的方法来解决低资源语言机器翻译的问题，通过增强高质量的句子对和使用基于 SentenceBERT 的过滤器来提高数据质量，将交叉熵损失和 KL 散度相结合，特别是通过伪目标句子实现无监督训练，实验证明该方法可以显著提高 NMT 基线性能

使用一致性正则化的半监督神经机器翻译技术——面向低资源语言