SPACE-2: Tree-Structured Semi-Supervised Contrastive Pre-training for Task-Oriented Dialog Understanding Wanwei He author Yinpei Dai author Binyuan Hui author Min Yang author Zheng Cao author Jianbo Dong author Fei Huang author Luo Si author Yongbin Li author 2022-10 text Proceedings of the 29th International Conference on Computational Linguistics Nicoletta Calzolari editor Chu-Ren Huang editor Hansaem Kim editor James Pustejovsky editor Leo Wanner editor Key-Sun Choi editor Pum-Mo Ryu editor Hsin-Hsi Chen editor Lucia Donatelli editor Heng Ji editor Sadao Kurohashi editor Patrizia Paggio editor Nianwen Xue editor Seokhwan Kim editor Younggyun Hahm editor Zhong He editor Tony Kyungil Lee editor Enrico Santus editor Francis Bond editor Seung-Hoon Na editor International Committee on Computational Linguistics Gyeongju, Republic of Korea conference publication he-etal-2022-space https://aclanthology.org/2022.coling-1.46/ 2022-10 553 569