On Search Strategies for Document-Level Neural Machine Translation
Christian Herold Hermann Ney
Compared to sentence-level systems, document-level neural machine translation
(NMT) models produce a more consistent output across a document and are able to
better resolve ambiguities within the input. There are many works on
document-level NMT, mostly focusing on modifying the model architecture or
training strategy to better accommodate the additional context-input. On the
other hand, in most works, the question on how to perform search with the
trained model is scarcely discussed, sometimes not mentioned at all. In this
work, we aim to answer the question how to best utilize a context-aware
translation model in decoding. We start with the most popular document-level
NMT approach and compare different decoding schemes, some from the literature
and others proposed by us. In the comparison, we are using both, standard
automatic metrics, as well as specific linguistic phenomena on three standard
document-level translation benchmarks. We find that most commonly used decoding
strategies perform similar to each other and that higher quality context
information has the potential to further improve the translation.