该文对机器翻译研究中的系统融合方法进行了全面综述和分析。根据在多系统输出结果的基础上进行融合的层次差异,我们将系统融合方法分为三类:句子级系统融合、短语级系统融合和词汇级系统融合。然后,针对这三种融合方法,该文分别介绍了它们各自具有代表性的研究工作,包括实现方法、置信度估计和解码算法等,并着重阐述了近年来使用广泛的词汇级系统融合方法中用于构造混淆网络的词对齐技术。最后,该文对这三类系统融合方法进行了比较、总结和展望。
This paper presents a survey of system combination for machine translation(MT).According to the different levels of combining the outputs from different machine translation systems,we classify the approaches to system combination into three types: sentence-level combination,phrase-level combination,and word-level combination.The representative work for each type is discussed in this paper,including the methods exploited,confidences estimated,and decoding algorithms,as well as the monolingual sentence alignment approaches which used to build the confusion network in the word-level system combination method.Finally,we discuss the three combination approaches and compare them with each other.The future development prospects of MT system combination are also discussed.