Exploring Context-Free Opinion Grammar for Aspect-Based Sentiment Analysis

Utilizing pre-trained generative models for sentiment element extraction has recently significantly enhanced aspect-based sentiment analysis benchmarks. Nonetheless, these models have two significant drawbacks: 1) high-computational cost in both the inference time and hardware requirement. 2) Lack of explicit modeling as they model the connections between sentiment elements with fragile natural or notational language target sequence. To overcome these challenges, we present a novel opinion tree parsing model designed to swiftly parse sentiment elements from an opinion tree. This approach not only accelerates the process but also explicitly unveils a more comprehensive and fully articulated aspect-level sentiment structure. Our method begins by introducing a pioneering context-free opinion grammar to standardize the opinion tree structure. Subsequently, we leverage a neural chart-based opinion tree parser to thoroughly explore the interconnections among sentiment elements and parse them into a structured opinion tree. Extensive experiments underscore the effectiveness of our proposed model and the capability of the opinion tree parser, particularly when coupled with the introduced context-free opinion grammar. Crucially, the results confirm the superior speed of our model compared to the SOTA baselines.