Group-Relative REINFORCE Is Secretly an Off-Policy Algorithm: Demystifying Some Myths About GRPO and Its Friends - Yao, Chaorui; Chen, Yanxi; Sun, Yuchang; Chen, Yushuo; Zhang, Wenhao; Pan, Xuchen; Li, Yaliang; Ding, Bolin (International Conference on Learning Representations, 2026)