RuCL: Stratified Rubric-Based Curriculum Learning for Multimodal Large Language Model Reasoning. - Yukun Chen; Jiaming Li 004; Longze Chen; Ze Gong; Jingpeng Li; Zhen Qin; Hengyu Chang; Ancheng Xu; Zhihao Yang; Hamid Alinejad-Rokny; Qiang Qu 001; Bo Zheng; et al. (CoRR, 2026)