The first decomposes a dialog system into a pipeline, typically including language understanding, dialog state tracking, action selection policy, and language generation (Levin et al., 2000;Singh et al., 2002;Williams and Young, 2007;Williams, 2008;Hori et al., 2009;Lee et al., 2009;Griol et al., 2008;Young et al., 2013;Li et al., 2014).
related to HCNs, past work has implemented the policy as feed-forward neural networks , trained with supervised learning followed by reinforcement learning .