Other more recent approaches include two-level reinforcement learning models (Takanobu et al., 2019), two layers of attention-based capsule network models , and self-attention with transformers (Verga et al., 2018).
(Miwa and Sasaki, 2014;Katiyar and Cardie, 2016;Zhang et al., 2017;Zheng et al., 2017;Verga et al., 2018;Takanobu et al., 2019) also seek to jointly learn the entities and relations among them together.