Paper: Improved Reordering for Shallow-n Grammar based Hierarchical Phrase-based Translation

ACL ID N12-1060
Title Improved Reordering for Shallow-n Grammar based Hierarchical Phrase-based Translation
Venue Annual Conference of the North American Chapter of the Association for Computational Linguistics
Session Main Conference
Year 2012
Authors

Shallow-n grammars (de Gispert et al., 2010) were introduced to reduce over-generation in the Hiero translation model (Chiang, 2005) re- sulting in much faster decoding and restricting reordering to a desired level for specific lan- guage pairs. However, Shallow-n grammars require parameters which cannot be directly optimized using minimum error-rate tuning by the decoder. This paper introduces some novel improvements to the translation model for Shallow-n grammars. We introduce two rules: a BITG-style reordering glue rule and a simpler monotonic concatenation rule. We use separate features for the new rules in our log- linear model allowing the decoder to directly optimize the feature weights. We show this formulation of Shallow-n hierarchical phrase- based translation is comparable in tr...