OptimSyn: Influence-Guided Rubrics Optimization for Synthetic Data Generation - Fan, Zhiting; Chen, Ruizhe; Hu, Tianxiang; Peng, Ru; Huang, Zenan; Xu, Haokai; Chen, Yixin; Wu, JIAN; Zhao, Junbo; Liu, Zuozhu (International Conference on Learning Representations, 2026)