ProtoEM: A Prototype-Enhanced Matching Framework for Event Relation
  Extraction
Zhilei Hu Zixuan Li Daozhu Xu Long Bai Cheng Jin Xiaolong Jin Jiafeng Guo Xueqi Cheng
Event Relation Extraction (ERE) aims to extract multiple kinds of relations
among events in texts. However, existing methods singly categorize event
relations as different classes, which are inadequately capturing the intrinsic
semantics of these relations. To comprehensively understand their intrinsic
semantics, in this paper, we obtain prototype representations for each type of
event relation and propose a Prototype-Enhanced Matching (ProtoEM) framework
for the joint extraction of multiple kinds of event relations. Specifically,
ProtoEM extracts event relations in a two-step manner, i.e., prototype
representing and prototype matching. In the first step, to capture the
connotations of different event relations, ProtoEM utilizes examples to
represent the prototypes corresponding to these relations. Subsequently, to
capture the interdependence among event relations, it constructs a dependency
graph for the prototypes corresponding to these relations and utilized a Graph
Neural Network (GNN)-based module for modeling. In the second step, it obtains
the representations of new event pairs and calculates their similarity with
those prototypes obtained in the first step to evaluate which types of event
relations they belong to. Experimental results on the MAVEN-ERE dataset
demonstrate that the proposed ProtoEM framework can effectively represent the
prototypes of event relations and further obtain a significant improvement over
baseline models.