We present the NTT translation system that is experimented for the evaluation campaign of “International Workshop on Spoken Language Translation (IWSLT).” The system consists of two primary components: a hierarchical phrase-based statistical machine translation system and a reranking sys tem. The former is conceptualized as a synchronous-CFG in which phrases are hierarchically combined using nonterminals. The latter uses a modified voted perceptron approach with large number of features. Experiments showed that our hierarchical phrase-based model outperformed a conventional phrase-based model. In addition, our reranking algorithm further boosted the performance.
['Taro Watanabe', 'Jun Suzuki', 'Hajime Tsukada', 'Hideki Isozaki']
NTT statistical machine translation for IWSLT 2006.