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.

Existing script event prediction task forcasts the subsequent event based on an event script chain. However, the evolution of historical events are more complicated in real world scenarios and the limited information provided by the event script chain also make it difficult to accurately predict subsequent events. This paper introduces a Causality Graph Event Prediction(CGEP) task that forecasting consequential event based on an Event Causality Graph (ECG). We propose a Semantic Enhanced Distance-sensitive Graph Prompt Learning (SeDGPL) Model for the CGEP task. In SeDGPL, (1) we design a Distance-sensitive Graph Linearization (DsGL) module to reformulate the ECG into a graph prompt template as the input of a PLM; (2) propose an Event-Enriched Causality Encoding (EeCE) module to integrate both event contextual semantic and graph schema information; (3) propose a Semantic Contrast Event Prediction (ScEP) module to enhance the event representation among numerous candidate events and predict consequential event following prompt learning paradigm. Experiment results validate our argument our proposed SeDGPL model outperforms the advanced competitors for the CGEP task.