Paper: solo leaderboards can't pick good collaborators; Shapley-based RL fixes it

shangbinfeng · x · 2026-10-22

New work from CMU researchers argues that LLMs are usually trained and evaluated alone, and leaderboards built to rank soloists miss what makes a good team player—solo RL can even make an LLM better alone but worse together. The paper proposes Compositional RL: training policies with GRPO where the reward is the model's Shapley marginal contribution to the multi-LLM system, plus methods to evaluate collaborators, including with frontier models.

Original post →

More from Research

Research channel →