PAT-Trees with the Deletion Function as the Learning Device for Linguistic Patterns Keh-Jiann Chen author Wen Tsuei author Lee-Feng Chien author 1998 text COLING 1998 Volume 1: The 17th International Conference on Computational Linguistics conference publication chen-etal-1998-pat https://aclanthology.org/C98-1038/ 1998