LearNAT: Learning NL2SQL with AST-guided Task Decomposition for Large Language Models - Liao, Weibin; Gao, Xin; Jia, Tianyu; Qiu, Rihong; Zhu, Yifan; Lin, Yang; Ma, Xinyu; Zhao, Junfeng; Wang, Yasha (International Conference on Learning Representations, 2026)