A Simple Pattern-matching Algorithm for Recovering Empty Nodes and their Antecedents Mark Johnson author 2002-07 text Proceedings of the 40th Annual Meeting of the Association for Computational Linguistics Pierre Isabelle editor Eugene Charniak editor Dekang Lin editor Association for Computational Linguistics Philadelphia, Pennsylvania, USA conference publication johnson-2002-simple 10.3115/1073083.1073107 https://aclanthology.org/P02-1018/ 2002-07 136 143