The Best of Both Worlds: Combining Recent Advances in Neural Machine Translation

George Foster
Llion Jones
Macduff Hughes
Mike Schuster
Niki J. Parmar
ACL'18 (2018) (to appear)

Abstract

The past year has witnessed rapid advances in sequence-to-sequence (seq2seq)
modeling for Machine Translation (MT). The classic RNN-based approaches to MT
were first out-performed by the convolutional seq2seq model, which was then
out-performed by the more recent Transformer model. Each of these new
approaches consists of a fundamental architecture accompanied by a set of
modeling and training techniques that are in principle applicable to other
seq2seq architectures. In this paper, we tease apart the new architectures and
their accompanying techniques in two ways. First, we identify several key
modeling and training techniques, and apply them to the RNN architecture,
yielding a new RNMT+ model that outperforms all of the three fundamental architectures
on the benchmark WMT'14 English to French and
English to German tasks. Second, we analyze the properties of each
fundamental seq2seq architecture and devise new hybrid architectures intended
to combine their strengths. Our hybrid models obtain further improvements,
outperforming the RNMT+ model on both benchmark datasets.