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Bibliographic Details
Main Authors: Huang, Wenhao, Zeng, Qingwen, Chen, Qiyue, Guo, Zijie, Sun, Yu, Yang, Cheng, Ouyang, Siru, Gesi, Jiri, Wu, Fang, Zhang, Jiayi, Chen, Huaming, Liu, Bang, Tang, Xiangru, Wu, Chenglin
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2605.18597
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Table of Contents:
  • Large language model (LLM) agents often rely on long sequences of low-level textual actions, resulting in large effective decision horizons and high inference cost. While prior work has focused on improving inference efficiency through system-level optimizations or prompt engineering, we argue that a key bottleneck lies in the representation of the action space itself. We propose Latent Action Reparameterization (LAR), a framework that learns a compact latent action space in which each latent action corresponds to a multi-step semantic behavior. By reparameterizing agent actions into latent units, LAR enables decision making over a shorter effective horizon while preserving the expressiveness of the original action space. Unlike hand-crafted macros or hierarchical controllers, latent actions are learned from agent trajectories and integrated directly into the model, allowing both planning and execution to operate over abstract action representations. Across a range of LLM-based agent benchmarks, LAR significantly reduces the effective action horizon and improves inference efficiency under fixed compute budgets. As a consequence, our approach achieves substantial reductions in action tokens and corresponding wall-clock inference time, while maintaining or improving task success rates. These results suggest that action representation learning is a critical and underexplored factor in scaling efficient LLM agent inference, complementary to advances in model architecture and hardware.