ProoFVer: Natural Logic Theorem Proving for Fact Verification Amrith Krishna author Sebastian Riedel author Andreas Vlachos author 2022 text journal article Transactions of the Association for Computational Linguistics continuing MIT Press Cambridge, MA periodical academic journal krishna-etal-2022-proofver 10.1162/tacl_a_00503 https://aclanthology.org/2022.tacl-1.59/ 2022 10 1013 1030