Generalizing Hierarchical Phrase-based Translation using Rules with Adjacent Nonterminals

Hendra Setiawan, Philip Resnik

Abstract: Hierarchical phrase-based translation (Hiero, (Chiang, 2005)) provides an attractive framework within which both short- and long-distance reorderings can be addressed consistently and efficiently. However, Hiero is generally implemented with a constraint preventing the creation of rules with adjacent nonterminals, because such rules introduce computational and modeling challenges. We introduce methods to address these challenges, and demonstrate that rules with adjacent nonterminals can improve Hiero's generalization power and lead to significant performance gains in Chinese-English translation.