To ensure a fair comparison, we employed the same settings for all NMT systems.
except for the maximum sequence length (seqlen, which was to 80), and the stopping iteration which was selected using development data, we used the default settings set out in (Bahdanau et al., 2014) for all NMT-based systems: the dimension of word embedding was 620, the dimension of hidden units was 1000, the batch size was 80, the source and target side vocabulary sizes were 30000, and the beam size for decoding was 12.