A popular way to tackle NLP problems with overlap between input and output is to equip seq2seq models with a copying mechanism (Jia and Liang, 2016;Zhao et al., 2019;Chen and Bansal, 2018;Gulcehre et al., 2016;See et al., 2017;Gu et al., 2016), usually borrowing ideas from pointer networks  to point to single tokens in the source sequence.
we use pointer networks to identify entire spans that are to be copied which results in a much more compact representation and faster decoding.