  Attention-based sequence-to-sequence model has proved successful in Neural
Machine Translation (NMT). However, the attention without consideration of
decoding history, which includes the past information in the decoder and the
attention mechanism, often causes much repetition. To address this problem, we
propose the decoding-history-based Adaptive Control of Attention (ACA) for the
NMT model. ACA learns to control the attention by keeping track of the decoding
history and the current information with a memory vector, so that the model can
take the translated contents and the current information into consideration.
Experiments on Chinese-English translation and the English-Vietnamese
translation have demonstrated that our model significantly outperforms the
strong baselines. The analysis shows that our model is capable of generating
translation with less repetition and higher accuracy. The code will be
available at https://github.com/lancopku
