RL-PLUS: Countering Capability Boundary Collapse of LLMs in Reinforcement Learning with Hybrid-policy Optimization

Fuente: arXiv
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Autori principali: Dong, Yihong, Jiang, Xue, Tao, Yongding, Liu, Huanyu, Zhang, Kechi, Mou, Lili, Cao, Rongyu, Ma, Yingwei, Chen, Jue, Li, Binhua, Jin, Zhi, Huang, Fei, Li, Yongbin, Li, Ge
Natura: Preprint
Pubblicazione: 2025
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author Dong, Yihong
Jiang, Xue
Tao, Yongding
Liu, Huanyu
Zhang, Kechi
Mou, Lili
Cao, Rongyu
Ma, Yingwei
Chen, Jue
Li, Binhua
Jin, Zhi
Huang, Fei
Li, Yongbin
Li, Ge
author_facet Dong, Yihong
Jiang, Xue
Tao, Yongding
Liu, Huanyu
Zhang, Kechi
Mou, Lili
Cao, Rongyu
Ma, Yingwei
Chen, Jue
Li, Binhua
Jin, Zhi
Huang, Fei
Li, Yongbin
Li, Ge
contents Reinforcement Learning with Verifiable Reward (RLVR) has significantly advanced the complex reasoning abilities of Large Language Models (LLMs). However, it struggles to break through the inherent capability boundaries of the base LLM, due to its essentially on-policy strategy coupled with LLM's immense action space and sparse reward. Critically, RLVR can lead to the capability boundary collapse, narrowing the LLM's problem-solving scope. To address this problem, we propose RL-PLUS, a novel hybrid-policy optimization approach for LLMs that synergizes internal exploitation with external data to achieve stronger reasoning capabilities and surpass the boundaries of base models. RL-PLUS integrates two core components, i.e., Multiple Importance Sampling to address distributional mismatch from external data, and Exploration-Based Advantage Function to guide the model towards high-value, unexplored reasoning paths. We provide both theoretical analysis and extensive experiments to demonstrate the superiority and generalizability of our approach. Compared with existing RLVR methods, RL-PLUS achieves 1) state-of-the-art performance on six math reasoning benchmarks; 2) superior performance on six out-of-distribution reasoning tasks; 3) consistent and significant gains across diverse model families, with average relative improvements up to 69.2\%. Moreover, the analysis of Pass@k curves indicates that RL-PLUS effectively resolves the capability boundary collapse problem.
format Preprint
id arxiv_https___arxiv_org_abs_2508_00222
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle RL-PLUS: Countering Capability Boundary Collapse of LLMs in Reinforcement Learning with Hybrid-policy Optimization
Dong, Yihong
Jiang, Xue
Tao, Yongding
Liu, Huanyu
Zhang, Kechi
Mou, Lili
Cao, Rongyu
Ma, Yingwei
Chen, Jue
Li, Binhua
Jin, Zhi
Huang, Fei
Li, Yongbin
Li, Ge
Artificial Intelligence
Computation and Language
Machine Learning
Reinforcement Learning with Verifiable Reward (RLVR) has significantly advanced the complex reasoning abilities of Large Language Models (LLMs). However, it struggles to break through the inherent capability boundaries of the base LLM, due to its essentially on-policy strategy coupled with LLM's immense action space and sparse reward. Critically, RLVR can lead to the capability boundary collapse, narrowing the LLM's problem-solving scope. To address this problem, we propose RL-PLUS, a novel hybrid-policy optimization approach for LLMs that synergizes internal exploitation with external data to achieve stronger reasoning capabilities and surpass the boundaries of base models. RL-PLUS integrates two core components, i.e., Multiple Importance Sampling to address distributional mismatch from external data, and Exploration-Based Advantage Function to guide the model towards high-value, unexplored reasoning paths. We provide both theoretical analysis and extensive experiments to demonstrate the superiority and generalizability of our approach. Compared with existing RLVR methods, RL-PLUS achieves 1) state-of-the-art performance on six math reasoning benchmarks; 2) superior performance on six out-of-distribution reasoning tasks; 3) consistent and significant gains across diverse model families, with average relative improvements up to 69.2\%. Moreover, the analysis of Pass@k curves indicates that RL-PLUS effectively resolves the capability boundary collapse problem.
title RL-PLUS: Countering Capability Boundary Collapse of LLMs in Reinforcement Learning with Hybrid-policy Optimization
topic Artificial Intelligence
Computation and Language
Machine Learning
url https://arxiv.org/abs/2508.00222