Date of Original Version

6-2014

Type

Article

Journal Title

Computational Linguistics

Volume

40

Issue

2

First Page

349

Last Page

401

Rights Management

© 2014 Association for Computational Linguistics The version of record is available online at http://dx.doi.org/10.1162/COLI_a_00175

Abstract or Description

Recent research has shown clear improvement in translation quality by exploiting linguistic syntax for either the source or target language. However, when using syntax for both languages (“tree-to-tree” translation), there is evidence that syntactic divergence can hamper the extraction of useful rules (Ding and Palmer 2005). Smith and Eisner (2006) introduced quasi-synchronous grammar, a formalism that treats non-isomorphic structure softly using features rather than hard constraints. Although a natural fit for translation modeling, its flexibility has proved challenging for building real-world systems. In this article, we present a tree-to-tree machine translation system inspired by quasi-synchronous grammar. The core of our approach is a new model that combines phrases and dependency syntax, integrating the advantages of phrase-based and syntax-based translation. We report statistically significant improvements over a phrasebased baseline on five of seven test sets across four language pairs. We also present encouraging preliminary results on the use of unsupervised dependency parsing for syntax-based machine translation.

DOI

10.1162/COLI_a_00175

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Published In

Computational Linguistics, 40, 2, 349-401.