“…Most recent works have focused on leveraging neural networks in this task (Chen et al, 2015;Nguyen and Grishman, 2015;Nguyen et al, 2016;Ghaeini et al, 2016;Feng et al, 2016). The existing approaches can be categorized into two classes: The first class is to improve ED through special learning techniques including adversarial training (Hong et al, 2018), knowledge distillation (Liu et al, 2019; and model pretraining (Yang et al, 2019). The second class is to improve ED by introducing extra resource, such as argument information , document information (Duan et al, 2017;Chen et al, 2018), multi-lingual information (Liu et al, 2018a(Liu et al, , 2019, knowledge base and syntactic information (Sha et al, 2018).…”