We present a counterfactual recognition (CR) task, the shared Task 5 of SemEval-2020. Counterfactuals describe potential outcomes (consequents) produced by actions or circumstances that did not happen or cannot happen and are counter to the facts (antecedent). Counterfactual thinking is an important characteristic of the human cognitive system; it connects antecedents and consequents with causal relations. Our task provides a benchmark for counterfactual recognition in natural language with two subtasks. Subtask-1 aims to determine whether a given sentence is a counterfactual statement or not. Subtask-2 requires the participating systems to extract the antecedent and consequent in a given counterfactual statement. During the SemEval-2020 official evaluation period, we received 27 submissions to Subtask-1 and 11 to Subtask-2. The data, baseline code, and leaderboard can be found at https://competitions.codalab.org/competitions/21691. The data and baseline code are also available at https://zenodo.org/record/3932442.

该研究提出并介绍一项计算机任务，即SemEval-2020第5项共享任务，该任务通过两个子任务为自然语言文本中的反事实语句的识别提供基准，其中第一子任务确定一个句子是否为反事实陈述，第二子任务要求识别出一个反事实陈述中的前置条件和结果，该任务旨在连接人类认知系统中的前后因果关系。

SemEval-2020任务5：反事实识别