Tractable Lexical-Functional Grammar Jürgen Wedekind author Ronald M Kaplan author 2020-09 text journal article Computational Linguistics continuing periodical academic journal wedekind-kaplan-2020-tractable 10.1162/coli_a_00384 https://aclanthology.org/2020.cl-3.1/ 2020-09 46 3 515 569