“…Despite the good performance of these models, one of their widely acknowledged intrinsic drawbacks is the generation of safe and commonplace responses (Sordoni et al, 2015) due to improper objective function (Li et al, 2016), lack of model variability (Serban et al, 2017;Zhao et al, 2017), weak conditional signal (Tao et al, 2018), and model over-confidence (Jiang and de Rijke, 2018). Such tendency has prompted the study of methods that improve diversity and has resulted in a wide variety of solutions, such as optimizing a different loss function (Li et al, 2016;, varying the latent space (Shao et al, 2019;, utilizing adversarial learning (Xu et al, 2018;Shetty et al, 2017;Shi et al, 2018), and leveraging non-conversational information (Wu et al, 2020;Su et al, 2020;Tu et al, 2019). Our work is different from all above in that we adopt a pipeline model which promotes diversity by generating a variety of candidates.…”