Semi-supervised approaches for NMT are often based on automatically creating pseudoparallel sentences through methods such as backtranslation (Irvine and Callison-Burch, 2013;Sennrich et al., 2016) or adding an auxiliary autoencoding task on monolingual data (Cheng et al., 2016;Currey et al., 2017).
we duplicate the number of parallel sentences by 5 times in the training data augmented with the reordered pairs.