Tree-Capsule: Tree-Structured Capsule Network for Improving Relation Extraction

Relation extraction benefits a variety of applications requiring relational understanding of unstructured texts, such as question answering. Recently, capsule network-based models have been proposed for improving relation extraction with better capability of modeling complex entity relations. However, they fail to capture the syntactic structure information of a sentence which has proven to be useful for relation extraction. In this paper, we propose a Tree-structured Capsule network based model for improving sentence-level Relation Extraction (TCRE), which seamlessly incorporates the syntax tree (Generally, syntax trees include constituent trees and dependency trees.) information (constituent tree is used in this work). Particularly, we design a novel tree-structured capsule network (Tree-Capsule network) to encode the constituent tree. Additionally, an entity-aware routing algorithm for Tree-Capsule network is proposed to pay attention to the critical relevant information, further improving the relation extraction of the target entities. Experimental results on standard datasets demonstrate that our TCRE significantly improves the performance of relation extraction by incorporating the syntactic structure information.