Unsupervised Extractive Summarization by Pre-training Hierarchical Transformers Shusheng Xu author Xingxing Zhang author Yi Wu author Furu Wei author Ming Zhou author 2020-11 text Findings of the Association for Computational Linguistics: EMNLP 2020 Trevor Cohn editor Yulan He editor Yang Liu editor Association for Computational Linguistics Online conference publication xu-etal-2020-unsupervised 10.18653/v1/2020.findings-emnlp.161 https://aclanthology.org/2020.findings-emnlp.161/ 2020-11 1784 1795