UMIX: Improving Importance Weighting for Subpopulation Shift via Uncertainty-Aware Mixup - Han, Zongbo; Liang, Zhipeng; Yang, Fan; Liu, Liu; Li, Lanqing; Bian, Yatao; Zhao, Peilin; Wu, Bingzhe; Zhang, Changqing; Yao, Jianhua (Advances in Neural Information Processing Systems, 2022)