The user simulator can provide infinite simulated experiences without additional cost, and the trained system can be deployed and then fine-tuned through interactions with real users (Su et al., 2016;Zhao and Eskenazi, 2016;Williams et al., 2017;Dhingra et al., 2017;Liu and Lane, 2017;Peng et al., 2017b;Budzianowski et al., 2017;Peng et al., 2017a;Tang et al., 2018).
due to the complexity of real conversations and biases in the design of user simulators, there always exists the discrepancy between real users and simulated users.