“…Early works on paraphrase generation mainly focus on rule-based (McKeown, 1983;Meteer and Shaked, 1988), grammar-based (Narayan et al, 2016), lexicon-based (Bolshakov and Gelbukh, 2004;Kauchak and Barzilay, 2006), and statistical machine translation (SMT)-based methods (Kauchak and Barzilay, 2006;Zhao et al, 2009). Recently, with the release of large-scale paraphrase datasets, sequence-to-sequence (seq2seq) models (Prakash et al, 2016;Kajiwara, 2019;Li et al, 2018;Gupta et al, 2018;Shakeri and Sethy, 2019;Yang et al, 2019) have become the dominant technique in the field of paraphrase generation.…”