SummEval: Re-evaluating Summarization Evaluation Alexander R Fabbri author Wojciech Kryściński author Bryan McCann author Caiming Xiong author Richard Socher author Dragomir Radev author 2021 text journal article Transactions of the Association for Computational Linguistics continuing MIT Press Cambridge, MA periodical academic journal fabbri-etal-2021-summeval 10.1162/tacl_a_00373 https://aclanthology.org/2021.tacl-1.24/ 2021 9 391 409