tailieunhanh - Báo cáo khoa học: "Word Alignment with Synonym Regularization"

We present a novel framework for word alignment that incorporates synonym knowledge collected from monolingual linguistic resources in a bilingual probabilistic model. Synonym information is helpful for word alignment because we can expect a synonym to correspond to the same word in a different language. We design a generative model for word alignment that uses synonym information as a regularization term. | Word Alignment with Synonym Regularization Hiroyuki Shindo Akinori Fujino and Masaaki Nagata NTT Communication Science Laboratories NTT Corp. 2-4 Hikaridai Seika-cho Soraku-gun Kyoto 619-0237 Japan shindo @ Abstract We present a novel framework for word alignment that incorporates synonym knowledge collected from monolingual linguistic resources in a bilingual probabilistic model. Synonym information is helpful for word alignment because we can expect a synonym to correspond to the same word in a different language. We design a generative model for word alignment that uses synonym information as a regularization term. The experimental results show that our proposed method significantly improves word alignment quality. 1 Introduction Word alignment is an essential step in most phrase and syntax based statistical machine translation SMT . It is an inference problem of word correspondences between different languages given parallel sentence pairs. Accurate word alignment can induce high quality phrase detection and translation probability which leads to a significant improvement in SMT performance. Many word alignment approaches based on generative models have been proposed and they learn from bilingual sentences in an unsupervised manner Vogel et al. 1996 Och and Ney 2003 Fraser and Marcu 2007 . One way to improve word alignment quality is to add linguistic knowledge derived from a monolingual corpus. This monolingual knowledge makes it easier to determine corresponding words correctly. For instance functional words in one language tend to correspond to functional words in another language Deng and Gao 2007 and the syntactic dependency of words in each language can help the alignment process Ma et al. 2008 . It has been shown that such grammatical information works as a constraint in word alignment models and improves word alignment quality. A large number of monolingual lexical semantic resources such as .