How do Transformers Learn Implicit Reasoning? - Ye, Jiaran; Yao, Zijun; Huang, Zhidian; Pan, Liangming; Liu, Jinxin; Bai, Yushi; Xin, Amy; Weichuan, Liu; Che, Xiaoyin; Hou, Lei; Li, Juanzi (Advances in Neural Information Processing Systems, 2025)