Cluster-Former: Clustering-based Sparse Transformer for Question Answering Shuohang Wang author Luowei Zhou author Zhe Gan author Yen-Chun Chen author Yuwei Fang author Siqi Sun author Yu Cheng author Jingjing Liu author 2021-08 text Findings of the Association for Computational Linguistics: ACL-IJCNLP 2021 Chengqing Zong editor Fei Xia editor Wenjie Li editor Roberto Navigli editor Association for Computational Linguistics Online conference publication wang-etal-2021-cluster 10.18653/v1/2021.findings-acl.346 https://aclanthology.org/2021.findings-acl.346/ 2021-08 3958 3968