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<Paper uid="H05-1095">
  <Title>Proceedings of Human Language Technology Conference and Conference on Empirical Methods in Natural Language Processing (HLT/EMNLP), pages 755-762, Vancouver, October 2005. c(c)2005 Association for Computational Linguistics Translating with non-contiguous phrases</Title>
  <Section position="8" start_page="760" end_page="761" type="concl">
    <SectionTitle>
7 Conclusions
</SectionTitle>
    <Paragraph position="0"> In this paper, we have proposed a phrase-based statistical machine translation method based on non-contiguous phrases. We have also presented a estimation procedure for the parameters of a log-linear translation model, that maximizes a smooth version of the NIST scoring function, and therefore lends itself to standard gradient-based optimization techniques. null From our experiments with these new methods, we essentially draw two conclusions. The first and most obvious is that non-contiguous bi-phrases can indeed be fruitful in phrase-based statistical machine translation. While we are not yet able to characterize which bi-phrases are most helpful, some of those that we are currently capable of extracting are well suited to cover some short-distance phenomena.</Paragraph>
    <Paragraph position="1">  The second conclusion is that alignment quality is crucial in producing good translations with phrase-based methods. While this may sound obvious, our experiments shed some light on two specific aspects of this question. The first is that the alignment method that produces the most useful bi-phrases need not be the one with the best alignment error rate (AER). The second is that, depending on the alignments one starts with, constructing increasingly large bi-phrases does not necessarily lead to better translations. Some of our best results were obtained with relatively small libraries (just over 200,000 entries) of short bi-phrases. In other words, it's not how many bi-phrases you have, it's how good they are. This is the line of research that we intend to pursue in the near future.</Paragraph>
  </Section>
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