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EPIG-Tree: Compute-Optimal Branching for Gradient-Efficient Reinforcement Learning

arXiv · Artificial Intelligence · article · Sep 17, 2026 · UTC

Reward-based reinforcement learning for language models, exemplified by Group Relative Policy Optimization (GRPO), collapses an entire stochastic trajectory into a single scalar reward. This is clean and scalable, but it explores and allocates reward inefficiently: a trajectory may contain many causal decisions, recovery attempts, and environment-randomness events, yet every token or action inherits one trajectory-level advantage. We study tree-based rollout construction as a compute-allocation problem for policy-gradient estimation. Our central claim is that branches should be placed not wher

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Evidence & attribution

First collected: 2026-09-19T20:26:32.566Z. This is not the publication date.