Cross-Supervised Joint-Event-Extraction with Heterogeneous Information Networks

TL;DR

This paper introduces a novel cross-supervised mechanism and leverages heterogeneous information networks to improve joint-event extraction, effectively addressing sparse co-occurrence issues and outperforming existing methods.

Contribution

The paper proposes a cross-supervised mechanism and utilizes heterogeneous information networks to enhance joint-event extraction performance.

Findings

Outperforms state-of-the-art methods in entity and trigger extraction

Effectively addresses sparse co-occurrence relationships

Demonstrates robustness across four real-world datasets

Abstract

Joint-event-extraction, which extracts structural information (i.e., entities or triggers of events) from unstructured real-world corpora, has attracted more and more research attention in natural language processing. Most existing works do not fully address the sparse co-occurrence relationships between entities and triggers, which loses this important information and thus deteriorates the extraction performance. To mitigate this issue, we first define the joint-event-extraction as a sequence-to-sequence labeling task with a tag set composed of tags of triggers and entities. Then, to incorporate the missing information in the aforementioned co-occurrence relationships, we propose a Cross-Supervised Mechanism (CSM) to alternately supervise the extraction of either triggers or entities based on the type distribution of each other. Moreover, since the connected entities and triggers naturally form a heterogeneous information network (HIN), we leverage the latent pattern along meta-paths for a given corpus to further improve the performance of our proposed method. To verify the effectiveness of our proposed method, we conduct extensive experiments on four real-world datasets as well as compare our method with state-of-the-art methods. Empirical results and analysis show that our approach outperforms the state-of-the-art methods in both entity and trigger extraction.