ARFlow: Auto-regressive Optical Flow Estimation for Arbitrary-Length Videos via Progressive Next-Frame Forecasting - Liu, Jiuming; Liu, Mengmeng; Zhu, Siting; Zhang, Yunpeng; Li, Jiangtao; Yang, Michael; Nex, Francesco; Cheng, Hao; Wang, Hesheng (International Conference on Learning Representations, 2026)