In this episode, we discuss Reverse-Engineered Reasoning for Open-Ended Generation by Haozhe Wang, Haoran Que, Qixin Xu, Minghao Liu, Wangchunshu Zhou, Jiazhan Feng, Wanjun Zhong, Wei Ye, Tong Yang, Wenhao Huang, Ge Zhang, Fangzhen Lin. The paper introduces REverse-Engineered Reasoning (REER), a novel backward approach that uncovers deep reasoning steps from known good solutions instead of forward trial-and-error or imitation. Using REER, the authors create DeepWriting-20K, a large dataset of reasoning trajectories for open-ended tasks, and train DeepWriter-8B, a model that outperforms strong open-source baselines. DeepWriter-8B also matches or exceeds the performance of leading proprietary models like GPT-4o and Claude 3.5.