Semi-Supervised Learning for Semantic Relation Classification using Stratified Sampling Strategy Longhua Qian author Guodong Zhou author Fang Kong author Qiaoming Zhu author 2009-08 text Proceedings of the 2009 Conference on Empirical Methods in Natural Language Processing Philipp Koehn editor Rada Mihalcea editor Association for Computational Linguistics Singapore conference publication qian-etal-2009-semi https://aclanthology.org/D09-1149/ 2009-08 1437 1445