Named Entity Recognition as Graph Classification

Ismail Harrando, Raphael Troncy

Keywords: Named Entity Recognition, Graph Classification, Knowledge Graph, Knowledge Injection

TL;DR: To facilitate the injection of external world knowledge to the task of Named Entity Recognition, we propose to approach it as a Graph Classification Task, where every word is a represented as a graph that contains its context and external knowledge.

Abstract: Injecting real-world information (typically contained in Knowledge Graphs) and human expertise into an end-to-end training pipeline for Natural Language Processing models is an open challenge. In this preliminary work, we propose to approach the task of Named Entity Recognition, which is traditionally viewed as a Sequence Labeling problem, as a Graph Classification problem, where every word is represented as a node in a graph. This allows to embed contextual information as well as other external knowledge relevant to each token, such as gazetteer mentions, morphological form, and linguistic tags. We experiment with a variety of graph modeling techniques to represent words, their contexts, and external knowledge, and we evaluate our approach on the standard CoNLL-2003 dataset. We obtained promising results when integrating external knowledge through the use of graph representation in comparison to the dominant end-to-end training paradigm.