arXiv AI By Yun Kim, Nojun Kwak

Advancing Entropy-Level Credit Assignment in RLVR via Proximal Entropy Policy Optimization

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The paper introduces Proximal Entropy Policy Optimization (PEPO), a method that assigns token‑level advantages in reinforcement learning for language models based on a local measure of entropy called proximal entropy. Unlike prior approaches that use global token entropy, PEPO evaluates importance relative to neighboring tokens, making it invariant to prompt difficulty and positional effects. Experiments on Qwen3 and Llama‑3.2 models show PEPO outperforms GRPO and other entropy‑based baselines in mathematical reasoning tasks.

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arXiv AI
Sep 15

HISPO: Hierarchical Importance-Sampling Policy Optimization with Entropy-Derived Segments

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arXiv AI
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arXiv:2606. 19771v1 Announce Type: new Abstract: Reinforcement Learning with Verifiable Rewards (RLVR) has significantly advanced Large Language Model (LLM) reasoning; however, it faces a fundamental optimization instability: uniform token updates precipitate entropy collapse, leading to premature convergence to suboptimal strategies, whereas excessive Shannon Entropy maximization can cause entropy explosion, driving blind exploration toward incoherent reasoning chains.

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