This paper aims to identify directional causal relations between events, including the existence and direction of causality. Previous studies mainly adopt prompt learning paradigm to predict a causal answer word based on a Pre-trained Language Model (PLM) for causality existence identification. However, the indecision in selecting answer words from some synonyms and the confusion of indicating opposite causal directions with the same answer word raise more challenges in directional causality identification. Inspired by the strong capabilities of pre-trained Generative Language Models (GLMs) in generating responses or statements, we propose to instruct a GLM to generate causality statements and identify directional event causality by evaluating the generated statements. Specifically, we propose an Instructive Generation and Statement Evaluation method to identify both the existence and direction of causality. We first fine-tune a GLM to instructively generate causality statements based on event description inputs. Then, we evaluate the rationality of the generated statements to determine the existence and direction of event causalities. Experiments on the ESC and MAVEN datasets show that our method significantly outperforms state-of-the-art algorithms, even with fewer training data.

“零样本关系抽取(ZSRE)旨在从可见关系中学习提取不可见关系的能力。一些研究表明:将样本语句与关系描述匹配进而预测不可见关系的方法,可以有效完成零样本关系抽取任务。然而,现有的匹配框架方法很少统一样本语句与关系描述的特征空间,缺乏对二者特征进行对齐。因此,本文提出一种为匹配框架零样本关系抽取而设计的统一特征空间构建方法。统一样本语句与关系描述的编码模块,并在此基础上引入特征相似损失。同时,为了减轻特征在空间上的聚合现象,引入特征均匀化模块,旨在构建特征更加均匀化的特征空间。本文所提出的方法实现了性能上的提升。与之前最佳的结果相比,在FewRel和Wiki-ZSL数据集上F1值平均提高1.6%和3.4%,体现了统一特征空间构建以及特征均匀化模块的有效性。”

“机器阅读理解(Machine Reading Comprehension, MRC)任务旨在让机器回答给定上下文的问题来测试机器理解自然语言的能力。目前,基于大规模预训练语言模型的神经机器阅读理解模型已经取得重要进展,但在涉及答案要素、线索要素和问题要素跨标点句、远距离关联时,答案抽取的准确率还有待提升。本文通过篇章内话头话体结构分析,建立标点句间远距离关联关系、补全共享缺失成分,辅助机器阅读理解答案抽取;设计和实现融合话头话体结构信息的机器阅读理解模型,在公开数据集CMRC2018上的实验结果表明,模型的F1值相对于基线模型提升2.4%,EM值提升6%。”

For the task of relation extraction, distant supervision is an efficient approach to generate labeled data by aligning knowledge base with free texts. The essence of it is a challenging incomplete multi-label classification problem with sparse and noisy features. To address the challenge, this work presents a novel nonparametric Bayesian formulation for the task. Experiment results show substantially higher top precision improvements over the traditional state-of-the-art approaches.