Discovery of Dependency Tree Patterns for Relation Extraction Hongzhi Xu author Changjian Hu author Guoyang Shen author 2009-12 text Proceedings of the 23rd Pacific Asia Conference on Language, Information and Computation, Volume 2 Olivia Kwong editor City University of Hong Kong Hong Kong conference publication xu-etal-2009-discovery https://aclanthology.org/Y09-2050/ 2009-12 851 858