Formal Language Recognition by Hard Attention Transformers: Perspectives from Circuit Complexity Yiding Hao author Dana Angluin author Robert Frank author 2022 text journal article Transactions of the Association for Computational Linguistics continuing MIT Press Cambridge, MA periodical academic journal hao-etal-2022-formal 10.1162/tacl_a_00490 https://aclanthology.org/2022.tacl-1.46/ 2022 10 800 810