1,104 research outputs found
Improving Lexical Choice in Neural Machine Translation
We explore two solutions to the problem of mistranslating rare words in
neural machine translation. First, we argue that the standard output layer,
which computes the inner product of a vector representing the context with all
possible output word embeddings, rewards frequent words disproportionately, and
we propose to fix the norms of both vectors to a constant value. Second, we
integrate a simple lexical module which is jointly trained with the rest of the
model. We evaluate our approaches on eight language pairs with data sizes
ranging from 100k to 8M words, and achieve improvements of up to +4.3 BLEU,
surpassing phrase-based translation in nearly all settings.Comment: Accepted at NAACL HLT 201
Translating Phrases in Neural Machine Translation
Phrases play an important role in natural language understanding and machine
translation (Sag et al., 2002; Villavicencio et al., 2005). However, it is
difficult to integrate them into current neural machine translation (NMT) which
reads and generates sentences word by word. In this work, we propose a method
to translate phrases in NMT by integrating a phrase memory storing target
phrases from a phrase-based statistical machine translation (SMT) system into
the encoder-decoder architecture of NMT. At each decoding step, the phrase
memory is first re-written by the SMT model, which dynamically generates
relevant target phrases with contextual information provided by the NMT model.
Then the proposed model reads the phrase memory to make probability estimations
for all phrases in the phrase memory. If phrase generation is carried on, the
NMT decoder selects an appropriate phrase from the memory to perform phrase
translation and updates its decoding state by consuming the words in the
selected phrase. Otherwise, the NMT decoder generates a word from the
vocabulary as the general NMT decoder does. Experiment results on the Chinese
to English translation show that the proposed model achieves significant
improvements over the baseline on various test sets.Comment: Accepted by EMNLP 201
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