Search-Based Credit Assignment for Offline Preference-Based Reinforcement Learning

Fuente: arXiv
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Main Authors: Gao, Xiancheng, Shi, Yufeng, Zhou, Wengang, Li, Houqiang
Format: Preprint
Published: 2025
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author Gao, Xiancheng
Shi, Yufeng
Zhou, Wengang
Li, Houqiang
author_facet Gao, Xiancheng
Shi, Yufeng
Zhou, Wengang
Li, Houqiang
contents Offline reinforcement learning refers to the process of learning policies from fixed datasets, without requiring additional environment interaction. However, it often relies on well-defined reward functions, which are difficult and expensive to design. Human feedback is an appealing alternative, but its two common forms, expert demonstrations and preferences, have complementary limitations. Demonstrations provide stepwise supervision, but they are costly to collect and often reflect limited expert behavior modes. In contrast, preferences are easier to collect, but it is unclear which parts of a behavior contribute most to a trajectory segment, leaving credit assignment unresolved. In this paper, we introduce a Search-Based Preference Weighting (SPW) scheme to unify these two feedback sources. For each transition in a preference labeled trajectory, SPW searches for the most similar state-action pairs from expert demonstrations and directly derives stepwise importance weights based on their similarity scores. These weights are then used to guide standard preference learning, enabling more accurate credit assignment that traditional approaches struggle to achieve. We demonstrate that SPW enables effective joint learning from preferences and demonstrations, outperforming prior methods that leverage both feedback types on challenging robot manipulation tasks.
format Preprint
id arxiv_https___arxiv_org_abs_2508_15327
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Search-Based Credit Assignment for Offline Preference-Based Reinforcement Learning
Gao, Xiancheng
Shi, Yufeng
Zhou, Wengang
Li, Houqiang
Artificial Intelligence
Machine Learning
Offline reinforcement learning refers to the process of learning policies from fixed datasets, without requiring additional environment interaction. However, it often relies on well-defined reward functions, which are difficult and expensive to design. Human feedback is an appealing alternative, but its two common forms, expert demonstrations and preferences, have complementary limitations. Demonstrations provide stepwise supervision, but they are costly to collect and often reflect limited expert behavior modes. In contrast, preferences are easier to collect, but it is unclear which parts of a behavior contribute most to a trajectory segment, leaving credit assignment unresolved. In this paper, we introduce a Search-Based Preference Weighting (SPW) scheme to unify these two feedback sources. For each transition in a preference labeled trajectory, SPW searches for the most similar state-action pairs from expert demonstrations and directly derives stepwise importance weights based on their similarity scores. These weights are then used to guide standard preference learning, enabling more accurate credit assignment that traditional approaches struggle to achieve. We demonstrate that SPW enables effective joint learning from preferences and demonstrations, outperforming prior methods that leverage both feedback types on challenging robot manipulation tasks.
title Search-Based Credit Assignment for Offline Preference-Based Reinforcement Learning
topic Artificial Intelligence
Machine Learning
url https://arxiv.org/abs/2508.15327