To obtain the long-term dependency vector representation, we use a bi-directional LSTM (Schuster and Paliwal, 1997) as the text encoder.
the input sequence is transformed into a hidden state sequence H = (h 1 , h 2 , ..., h m ) by concatenating the representations of the forward and backward hidden states the initiated encoder hidden state h 0 is a zero vector, and the last encoder hidden state h m is used for initiating the skill decoder.