基于约束的神经机器翻译

神经机器翻译是近几年出现并快速发展的一种深度学习驱动的新型机器翻译模式,目前已成为机器翻译学术和工业界广为接受的主流技术.本文总结了我们在神经机器翻译方面的工作,特别是在各种信息和知识约束条件下提出的一系列神经机器翻译模型和方法,具体包括隐变量约束的变分神经机器翻译模型、单词与短语级统计机器翻译译文推荐与约束模型、源端句法结构约束模型.除此之外,本文也对神经机器翻译未来发展进行了初步思考和展望.国家自然科学基金优秀青年基金(批准号:61622209)资助项

Variational decoding for statistical machine translation

Statistical models in machine translation exhibit spurious ambiguity. That is, the probability of an output string is split among many distinct derivations (e.g., trees or segmentations). In principle, the goodness of a string is measured by the total probability of its many derivations. However, finding the best string (e.g., during decoding) is then computationally intractable. Therefore, most systems use a simple Viterbi approximation that measures the goodness of a string using only its most probable derivation. Instead, we develop a variational approximation, which considers all the derivations but still allows tractable decoding. Our particular variational distributions are parameterized as n-gram models. We also analytically show that interpolating these n-gram models for different n is similar to minimumrisk decoding for BLEU (Tromble et al., 2008). Experiments show that our approach improves the state of the art.