Finally, we use the final backward hidden state as the initial hidden state of the decoder.
the decoder is to generate a response Y given the hidden representations of the input utterance X under some specificity level denoted by the control variable s. at step t, we define the probability of generating any target word y t by a "mixture" of probabilities: where p M (y t ) denotes the semantic-based generation probability, p S (y t ) denotes the specificitybased generation probability, β and γ are the coefficients.