“…The second further proposes the objectives that aligns with the goals of the conversation more effectively, such as MMI (Li et al, 2016a), CVAE (Serban et al, 2017b;Gu et al, 2019;Sun et al, 2021), RL (Li et al, 2016b;Zhang et al, 2018a;, and GAN Feng et al, 2020a). The third tries to endow the responses with topic (Xing et al, 2017;Feng et al, 2020b), emotion (Zhou et al, 2018;Rashkin et al, 2019), and persona (Qian et al, 2017;Zhang et al, 2018b;Song et al, 2020). Recently, another line of work Roller et al, 2020;Adiwardana et al, 2020;Bao et al, 2020), called the pre-trained dialogue model, relies on an efficient neural network and large-scale datasets to further improve the response quality.…”