Parsing with Semidirectional Lambek Grammar is NP-Complete Jochen Dörre author 1996-06 text 34th Annual Meeting of the Association for Computational Linguistics Association for Computational Linguistics Santa Cruz, California, USA conference publication dorre-1996-parsing 10.3115/981863.981876 https://aclanthology.org/P96-1013/ 1996-06 95 100