3 We first review existing methods to counter the length problem and then propose new ones to address their limitations.
in recent years, neural machine translation (NMT) has surpassed traditional phrase-based or syntaxbased machine translation, becoming the new state of the art in MT (Kalchbrenner and Blunsom, 2013;Sutskever et al., 2014;Bahdanau et al., 2014).