Although various methods have been developed (Zhao et al., 2009;Quirk et al., 2004;Barzilay and Lee, 2003), the recent progress on paraphrase generation is mainly from neural network modeling (Prakash et al., 2016).
the encoder-decoder framework is widely adopted (Cho et al., 2015), where the encoder takes source sentences as inputs and the decoder generates the corresponding paraphrase for each input sentence.