EIP: Weighted Ranking of LLMs by Quantifying Question Difficulty - Hu, Xingjian; Zhang, Ziqian; Huang, Yue; Zhang, Kai; Chen, Ruoxi; Liu, Yixin; Wen, Qingsong; Xu, Kaidi; Zhang, Xiangliang; Gong, Neil; Sun, Lichao (International Conference on Learning Representations, 2026)