In supervised NMT settings, combining multiple languages to jointly train an NMT system has been found to be successful in improving the performance (Dong et al., 2015;Firat et al., 2016;Johnson et al., 2017).
from Table 1, we observe that proposed multilingual model outperforms the separately trained bilingual models for all translation directions on both test sets with a maximum improvement of 1.48 BLEU points for for Spanish to English on newstest2013.