Improving alignment for SMT by reordering and augmenting the training corpus

  • Authors:
  • Maria Holmqvist;Sara Stymne;Jody Foo;Lars Ahrenberg

  • Affiliations:
  • Linköping University, Sweden;Linköping University, Sweden;Linköping University, Sweden;Linköping University, Sweden

  • Venue:
  • StatMT '09 Proceedings of the Fourth Workshop on Statistical Machine Translation
  • Year:
  • 2009

Quantified Score

Hi-index 0.01

Visualization

Abstract

We describe the LIU systems for English-German and German-English translation in the WMT09 shared task. We focus on two methods to improve the word alignment: (i) by applying Giza++ in a second phase to a reordered training corpus, where reordering is based on the alignments from the first phase, and (ii) by adding lexical data obtained as high-precision alignments from a different word aligner. These methods were studied in the context of a system that uses compound processing, a morphological sequence model for German, and a part-of-speech sequence model for English. Both methods gave some improvements to translation quality as measured by Bleu and Meteor scores, though not consistently. All systems used both out-of-domain and in-domain data as the mixed corpus had better scores in the baseline configuration.