Strong Equivalence of TAG and CCG Lena Katharina Schiffer author Andreas Maletti author 2021 text journal article Transactions of the Association for Computational Linguistics continuing MIT Press Cambridge, MA periodical academic journal schiffer-maletti-2021-strong 10.1162/tacl_a_00393 https://aclanthology.org/2021.tacl-1.43/ 2021 9 707 720