PABU: Progress-Aware Belief Update for Efficient LLM Agents

Fuente: arXiv
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Main Authors: Jiang, Haitao, Ge, Lin, Cai, Hengrui, Song, Rui
Format: Preprint
Published: 2026
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author Jiang, Haitao
Ge, Lin
Cai, Hengrui
Song, Rui
author_facet Jiang, Haitao
Ge, Lin
Cai, Hengrui
Song, Rui
contents Large Language Model (LLM) agents commonly condition actions on full action-observation histories, which introduce task-irrelevant information that easily leads to redundant actions and higher inference cost. We propose Progress-Aware Belief Update (PABU), a belief-state framework that compactly represents an agent's state by explicitly modeling task progress and selectively retaining past actions and observations. At each step, the agent predicts its relative progress since the previous round and decides whether the newly encountered interaction should be stored, conditioning future decisions only on the retained subset. Across eight environments in the AgentGym benchmark, and using identical training trajectories, PABU achieves an 81.0% task completion rate, outperforming previous State of the art (SoTA) models with full-history belief by 23.9%. Additionally, PABU's progress-oriented action selection improves efficiency, reducing the average number of interaction steps to 9.5, corresponding to a 26.9% reduction. Ablation studies show that both explicit progress prediction and selective retention are necessary for robust belief learning and performance gains.
format Preprint
id arxiv_https___arxiv_org_abs_2602_09138
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle PABU: Progress-Aware Belief Update for Efficient LLM Agents
Jiang, Haitao
Ge, Lin
Cai, Hengrui
Song, Rui
Artificial Intelligence
Computation and Language
Large Language Model (LLM) agents commonly condition actions on full action-observation histories, which introduce task-irrelevant information that easily leads to redundant actions and higher inference cost. We propose Progress-Aware Belief Update (PABU), a belief-state framework that compactly represents an agent's state by explicitly modeling task progress and selectively retaining past actions and observations. At each step, the agent predicts its relative progress since the previous round and decides whether the newly encountered interaction should be stored, conditioning future decisions only on the retained subset. Across eight environments in the AgentGym benchmark, and using identical training trajectories, PABU achieves an 81.0% task completion rate, outperforming previous State of the art (SoTA) models with full-history belief by 23.9%. Additionally, PABU's progress-oriented action selection improves efficiency, reducing the average number of interaction steps to 9.5, corresponding to a 26.9% reduction. Ablation studies show that both explicit progress prediction and selective retention are necessary for robust belief learning and performance gains.
title PABU: Progress-Aware Belief Update for Efficient LLM Agents
topic Artificial Intelligence
Computation and Language
url https://arxiv.org/abs/2602.09138