Neural networks based models like Seq2Seq architecture (Vinyals and Le, 2015;Shang et al., 2015) are proven to be effective to generate valid responses for a dialogue system.
as revealed in many previous works (Li et al., 2016a;Wu et al., 2018), "safe reply" is still an open problem and lots of efforts are made to generate more informative responses (Li et al., 2016a;Mou et al., 2016;Li et al., 2016b;Qiu et al., 2017;He et al., 2017;.