HETFORMER: Heterogeneous Transformer with Sparse Attention for Long-Text Extractive Summarization Ye Liu author Jianguo Zhang author Yao Wan author Congying Xia author Lifang He author Philip Yu author 2021-11 text Proceedings of the 2021 Conference on Empirical Methods in Natural Language Processing Marie-Francine Moens editor Xuanjing Huang editor Lucia Specia editor Scott Wen-tau Yih editor Association for Computational Linguistics Online and Punta Cana, Dominican Republic conference publication liu-etal-2021-hetformer 10.18653/v1/2021.emnlp-main.13 https://aclanthology.org/2021.emnlp-main.13/ 2021-11 146 154