Many innovative deep RL methods (Ranzato et al., 2016;Wu et al., 2016;Paulus et al., 2018;Lamb et al., 2016) are developed to alleviate this issue by providing sentence-level feedback after generating a complete sentence, in addition to optimal transport usage (Napoles et al., 2012).
(2018) do, because we want to examine the repetition of sentence directly produced after training.