Ferryman as SemEval-2020 Task 5: Optimized BERT for Detecting Counterfactuals

Proceedings of the 14th International Workshop on Semantic Evaluation, pages 653–657 Barcelona, Spain (Online), December 12, 2020. 653 Ferryman at SemEval-2020 Task 5: Optimized BERT for Detecting Counterfactuals Weilong Chen, Yan Zhuang, Peng Wang, Feng Hong, Yan Wang, and Yanru Zhang∗ University of Electronic Science and Technology of China {chenweilong1995,delecisz}@std.uestc.edu.cn {wangpeng3314,fengfengis}@std.uestc.edu.cn {yanbo1990,yanruzhang}@uestc.edu.cn Abstract The main purpose of this article is to state the effect of using different methods and models for counterfactual determination and detection of causal knowledge. Nowadays, counterfactual reasoning has been widely used in various fields. In the realm of natural language process(NLP), counterfactual reasoning has huge potential to improve the correctness of a sentence. In the shared Task 5 of detecting counterfactual in SemEval 2020, we pre-process the officially given dataset according to case conversion, extract stem and abbreviation replacement. We use last-5 bidirectional encoder representation from bidirectional encoder representation from transformer (BERT)and term frequency–inverse document frequency (TF-IDF) vectorizer for counterfactual detection. Meanwhile, multi-sample dropout and cross validation are used to improve versatility and prevent problems such as poor generosity caused by overfitting. Finally, our team Ferryman ranked the 8th place in the sub-task 1 of this competition. 1 Introduction Counterfactual refers to a conditional statement in which the first clause is a past tense subjunctive statement expressing something contrary to fact, as in “If I had studied harder, I might have passed the exam”. Sometimes it can be used in practice to support the assumption that if events occurred differently in the past, what might have happened (Gentner and Yeh, 2005), as in “If Rose had not accepted doctor’s advice to cut the tumor, she might have been dead”. Since Rose is still alive, and it is impossible to come back to ask Rose to reject the advice. While in other cases, as in “ If a drop in crude oil prices had been factored out, the stock price would not be so low”, it is not the counterfactual that the drop in the price of crude oil, more than anything else, caused the stock market to plummet. Judging counterfactual is hard for the reason that it involves so many aspects of life such as economy, medical treatment. Besides, the exploration of causation is necessary. Reasoning is a very important and challenge task in the fields of the Natural Language Process and aims to analyze the internal causality of the sentence to find out whether the sentence is correct or not. In the causal relationship, the cause is partly responsible for the result, while the result partly depends on the cause. There is an inherent causal relationship among objective things. Through grasping the causal relationship of things, people can understand the nature of things comprehensively. As an important research direction of causal reasoning, counterfactual reasoning has been employed in many cognitive processes. According to the order, counterfactual thinking can be divided into upward counterfactual thinking and downward counterfactual thinking. The former one is the assumption that something has happened in the past, that if certain conditions …

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