Maintaining Common Ground in Dynamic Environments Takuma Udagawa author Akiko Aizawa author 2021 text journal article Transactions of the Association for Computational Linguistics continuing MIT Press Cambridge, MA periodical academic journal udagawa-aizawa-2021-maintaining 10.1162/tacl_a_00409 https://aclanthology.org/2021.tacl-1.59/ 2021 9 995 1011