PRIMERA: Pyramid-based Masked Sentence Pre-training for Multi-document Summarization Wen Xiao author Iz Beltagy author Giuseppe Carenini author Arman Cohan author 2022-05 text Proceedings of the 60th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers) Smaranda Muresan editor Preslav Nakov editor Aline Villavicencio editor Association for Computational Linguistics Dublin, Ireland conference publication xiao-etal-2022-primera 10.18653/v1/2022.acl-long.360 https://aclanthology.org/2022.acl-long.360/ 2022-05 5245 5263