ExpanRL: Hierarchical Reinforcement Learning for Course Concept Expansion in MOOCs Jifan Yu author Chenyu Wang author Gan Luo author Lei Hou author Juanzi Li author Jie Tang author Minlie Huang author Zhiyuan Liu author 2020-12 text Proceedings of the 1st Conference of the Asia-Pacific Chapter of the Association for Computational Linguistics and the 10th International Joint Conference on Natural Language Processing Kam-Fai Wong editor Kevin Knight editor Hua Wu editor Association for Computational Linguistics Suzhou, China conference publication yu-etal-2020-expanrl 10.18653/v1/2020.aacl-main.77 https://aclanthology.org/2020.aacl-main.77/ 2020-12 770 780