Ferhan Ture, Douglas W. Oard, and Philip Resnik
NAACL 2012
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The list of discussed topics follows the outline of the paper:

Differences from Carpuat 2009

• It is different: the decoder just gets additional features, but the decision is up to it – Carpuat 2009 just post-edits the outputs and substitutes the most likely variant everywhere
  • Using Carpuat 2009's approach directly in the decoder would influence neighboring words through LM, so even using this in the decoder and not as post-editing leads to a different outcome

Human translators and one sense per discourse

• This suggests that modelling human translators is the same as modelling one sense per discourse – this is suspicious
  • The authors do not state their evidence clearly.
  • One sense is not the same as one translation

Hiero

• The idea would most probably work the same in normal phrase-based SMT, but the authors use hierarchical phrase-based translation (Hiero)
  • Hiero is summarized in Fig. 1: the phrases may contain non-terminals (X, X1 etc.), which leads to a probabilistic CFG and bottom-up parsing
• The authors chose the cdec implementation of Hiero (which is implemented in several systems: Moses, cdec, Joshua etc.)
  • The choice was probably arbitrary, other systems would yield similar results

Forced decoding

• This means that the decoder is given source and target sentence and has to provide the rules/phrases that map from the source to the target
  • The decoder might be unable to find the appropriate rules (for unseen words)
  • It is a different decoder mode, for which it must be adjusted
  • Forced decoding is much more informative for Hiero translations than for “plain” phrase-based ones, since there are many different parse trees that yield the same target string, and not as much phrases