Knowing What, How and Why: A Near Complete Solution for Aspect-based Sentiment Analysis
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Target-based sentiment analysis or aspect-based sentiment analysis (ABSA) refers to addressing various sentiment analysis tasks at a fine-grained level, which includes but is not limited to aspect extraction, aspect sentiment classification, and opinion extraction. There exist many solvers for the above individual subtasks or a combination of two subtasks, which can work together to tell a complete story, i.e. the discussed aspect, the sentiment on it, and the cause of the sentiment. However, no previous ABSA research tried to provide a complete solution in one shot. In this paper, we introduce a sentiment triplet extraction task. Particularly, a sentiment triplet (What, How, Why) consists of the aspect being discussed, the sentiment polarity on it, and the opinions causing such a sentiment. For sentence, one triplet from "Waiters are very friendly and the pasta is simply average" could be (`Waiters', positive, `friendly'). We propose a two-stage framework to address this task. The first stage predicts what, how and why in a unified model, and then the second stage pairs up the predicted what's and why's from the same input sentence so as to output triplets. In the experiments, our framework has set a benchmark performance in this novel triplet extraction task. Meanwhile, our framework outperforms the state-of-the-art methods (with modifications to fit in the setting) and the strongest sequence taggers on several benchmark datasets.
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