… We investigate how neural, encoder-decoder translation systems output target strings of
appropriate lengths, finding that a collection of hidden units learns to explicitly implement
this functionality. … A remarkable feature of this simple neural MT (NMT) model is that it
produces translations of the right length. When we evaluate the system on previously
unseen test data, using BLEU (Papineni et al., 2002), we consistently find the length ratio
between MT outputs and human references translations to be very close to 1.0. Thus, no …