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Autori principali: Xu, Peiran, Li, Zhuohao, Xing, Xiaoying, Zhang, Guannan, Li, Debiao, Shi, Kunyu
Natura: Preprint
Pubblicazione: 2025
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Accesso online:https://arxiv.org/abs/2509.25598
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author Xu, Peiran
Li, Zhuohao
Xing, Xiaoying
Zhang, Guannan
Li, Debiao
Shi, Kunyu
author_facet Xu, Peiran
Li, Zhuohao
Xing, Xiaoying
Zhang, Guannan
Li, Debiao
Shi, Kunyu
contents Large Language Models (LLMs) increasingly rely on external tools such as search engines to solve complex agentic tasks that require reasoning and external knowledge retrieval. Recently, reinforcement learning with verifiable rewards (RLVR) has demonstrated its effectiveness in advancing capabilities of LLMs by rewarding the final answers via outcome rewards. While straightforward to supervise, outcome rewards only provide sparse signals and delayed feedback, which limits their effectiveness on long trajectories. Process rewards address this by evaluating intermediate steps, providing fine-grained supervision and encouraging grounded problem solving. However, it is notoriously hard to annotate step-wise labels, especially in non-verifiable process without "golden" answers. Furthermore, step-wise judgment requires the balance between local quality with contribution to the final outcome, as optimizing towards higher process reward may not always align with better final outcomes. To address the above challenges, we introduce Principle Process Reward (PPR), an RL approach that unifies principled step-level assessment and outcome verification. We train a principle-based reward model to improve the transparency and reliability of process evaluation, and further introduce a Reward Normalization (ReNorm) strategy to calibrate outcome and process rewards. Experiment results show that PPR achieves state-of-the-art performance across a wide range of benchmarks, demonstrating its impressive robustness and generalization. Our code and model collection is available in this link.
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id arxiv_https___arxiv_org_abs_2509_25598
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publishDate 2025
record_format arxiv
spellingShingle Hybrid Reward Normalization for Process-supervised Non-verifiable Agentic Tasks
Xu, Peiran
Li, Zhuohao
Xing, Xiaoying
Zhang, Guannan
Li, Debiao
Shi, Kunyu
Artificial Intelligence
Machine Learning
Large Language Models (LLMs) increasingly rely on external tools such as search engines to solve complex agentic tasks that require reasoning and external knowledge retrieval. Recently, reinforcement learning with verifiable rewards (RLVR) has demonstrated its effectiveness in advancing capabilities of LLMs by rewarding the final answers via outcome rewards. While straightforward to supervise, outcome rewards only provide sparse signals and delayed feedback, which limits their effectiveness on long trajectories. Process rewards address this by evaluating intermediate steps, providing fine-grained supervision and encouraging grounded problem solving. However, it is notoriously hard to annotate step-wise labels, especially in non-verifiable process without "golden" answers. Furthermore, step-wise judgment requires the balance between local quality with contribution to the final outcome, as optimizing towards higher process reward may not always align with better final outcomes. To address the above challenges, we introduce Principle Process Reward (PPR), an RL approach that unifies principled step-level assessment and outcome verification. We train a principle-based reward model to improve the transparency and reliability of process evaluation, and further introduce a Reward Normalization (ReNorm) strategy to calibrate outcome and process rewards. Experiment results show that PPR achieves state-of-the-art performance across a wide range of benchmarks, demonstrating its impressive robustness and generalization. Our code and model collection is available in this link.
title Hybrid Reward Normalization for Process-supervised Non-verifiable Agentic Tasks
topic Artificial Intelligence
Machine Learning
url https://arxiv.org/abs/2509.25598