Paper: Enlisting the Ghost: Modeling Empty Categories for Machine Translation

ACL ID P13-1081
Title Enlisting the Ghost: Modeling Empty Categories for Machine Translation
Venue Annual Meeting of the Association of Computational Linguistics
Session Main Conference
Year 2013
Authors

Empty categories (EC) are artificial ele- ments in Penn Treebanks motivated by the government-binding (GB) theory to ex- plain certain language phenomena such as pro-drop. ECs are ubiquitous in languages like Chinese, but they are tacitly ignored in most machine translation (MT) work because of their elusive nature. In this paper we present a comprehensive treat- ment of ECs by first recovering them with a structured MaxEnt model with a rich set of syntactic and lexical features, and then incorporating the predicted ECs into a Chinese-to-English machine translation task through multiple approaches, includ- ing the extraction of EC-specific sparse features. We show that the recovered empty categories not only improve the word alignment quality, but also lead to significant improvements in a...