Topic-aware hierarchical multi-attention network for text classification

Neural networks, primarily recurrent and convolutional Neural networks, have been proven successful in text classification. However, convolutional models could be limited when classification tasks are determined by long-range semantic dependency. While the recurrent ones can capture long-range dependency, the sequential architecture of which could constrain the training speed. Meanwhile, traditional networks encode the entire document in a single pass, which omits the hierarchical structure of the document. To address the above issues, this study presents T-HMAN, a Topic-aware Hierarchical Multiple Attention Network for text classification. A multi-head self-attention coupled with convolutional filters is developed to capture long-range dependency via integrating the convolution features from each attention head. Meanwhile, T-HMAN combines topic distributions generated by Latent Dirichlet Allocation (LDA) with sentence-level and document-level inputs respectively in a hierarchical architecture. The proposed model surpasses the accuracies of the current state-of-the-art hierarchical models on five publicly accessible datasets. The ablation study demonstrates that the involvement of multiple attention mechanisms brings significant improvement. The current topic distributions are fixed vectors generated by LDA, the topic distributions will be parameterized and updated simultaneously with the model weights in future work.