Simple Entity-Centric Questions Challenge Dense Retrievers Christopher Sciavolino author Zexuan Zhong author Jinhyuk Lee author Danqi Chen 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 sciavolino-etal-2021-simple 10.18653/v1/2021.emnlp-main.496 https://aclanthology.org/2021.emnlp-main.496/ 2021-11 6138 6148