47 research outputs found
Joint Extraction of Entities and Relations Based on a Novel Tagging Scheme
Joint extraction of entities and relations is an important task in
information extraction. To tackle this problem, we firstly propose a novel
tagging scheme that can convert the joint extraction task to a tagging problem.
Then, based on our tagging scheme, we study different end-to-end models to
extract entities and their relations directly, without identifying entities and
relations separately. We conduct experiments on a public dataset produced by
distant supervision method and the experimental results show that the tagging
based methods are better than most of the existing pipelined and joint learning
methods. What's more, the end-to-end model proposed in this paper, achieves the
best results on the public dataset
Contrastive Triple Extraction with Generative Transformer
Triple extraction is an essential task in information extraction for natural
language processing and knowledge graph construction. In this paper, we revisit
the end-to-end triple extraction task for sequence generation. Since generative
triple extraction may struggle to capture long-term dependencies and generate
unfaithful triples, we introduce a novel model, contrastive triple extraction
with a generative transformer. Specifically, we introduce a single shared
transformer module for encoder-decoder-based generation. To generate faithful
results, we propose a novel triplet contrastive training object. Moreover, we
introduce two mechanisms to further improve model performance (i.e., batch-wise
dynamic attention-masking and triple-wise calibration). Experimental results on
three datasets (i.e., NYT, WebNLG, and MIE) show that our approach achieves
better performance than that of baselines.Comment: Accepted by AAAI 202
A Hierarchical Framework for Relation Extraction with Reinforcement Learning
Most existing methods determine relation types only after all the entities
have been recognized, thus the interaction between relation types and entity
mentions is not fully modeled. This paper presents a novel paradigm to deal
with relation extraction by regarding the related entities as the arguments of
a relation. We apply a hierarchical reinforcement learning (HRL) framework in
this paradigm to enhance the interaction between entity mentions and relation
types. The whole extraction process is decomposed into a hierarchy of two-level
RL policies for relation detection and entity extraction respectively, so that
it is more feasible and natural to deal with overlapping relations. Our model
was evaluated on public datasets collected via distant supervision, and results
show that it gains better performance than existing methods and is more
powerful for extracting overlapping relations.Comment: To appear in AAAI 1
Relation Extraction using Explicit Context Conditioning
Relation Extraction (RE) aims to label relations between groups of marked
entities in raw text. Most current RE models learn context-aware
representations of the target entities that are then used to establish relation
between them. This works well for intra-sentence RE and we call them
first-order relations. However, this methodology can sometimes fail to capture
complex and long dependencies. To address this, we hypothesize that at times
two target entities can be explicitly connected via a context token. We refer
to such indirect relations as second-order relations and describe an efficient
implementation for computing them. These second-order relation scores are then
combined with first-order relation scores. Our empirical results show that the
proposed method leads to state-of-the-art performance over two biomedical
datasets.Comment: Accepted for Publication at NAACL 201
End-to-end neural relation extraction using deep biaffine attention
We propose a neural network model for joint extraction of named entities and
relations between them, without any hand-crafted features. The key contribution
of our model is to extend a BiLSTM-CRF-based entity recognition model with a
deep biaffine attention layer to model second-order interactions between latent
features for relation classification, specifically attending to the role of an
entity in a directional relationship. On the benchmark "relation and entity
recognition" dataset CoNLL04, experimental results show that our model
outperforms previous models, producing new state-of-the-art performances.Comment: Proceedings of the 41st European Conference on Information Retrieval
(ECIR 2019), to appea