ReMA: Learning to Meta-Think for LLMs with Multi-agent Reinforcement Learning - Wan, Ziyu; Li, Yunxiang; Wen, Xiaoyu; Song, Yan; Wang, Hanjing; Yang, Linyi; Schmidt, Mark; Wang, Jun; Zhang, Weinan; Hu, Shuyue; Wen, Ying (Advances in Neural Information Processing Systems, 2025)