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Main Authors: Hu, Zhengpei, Li, Kai, Fu, Dapeng, Zeng, Chang, Li, Yue, Tang, Yuanhao, Huang, Jianqiang
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2603.19635
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author Hu, Zhengpei
Li, Kai
Fu, Dapeng
Zeng, Chang
Li, Yue
Tang, Yuanhao
Huang, Jianqiang
author_facet Hu, Zhengpei
Li, Kai
Fu, Dapeng
Zeng, Chang
Li, Yue
Tang, Yuanhao
Huang, Jianqiang
contents The exponential expansion of context windows in LLMs has unlocked capabilities for long-document understanding but introduced severe bottlenecks in inference latency and information utilization. Existing compression methods often suffer from high training costs or semantic fragmentation due to aggressive token pruning. In this paper, we propose BEAVER, a novel training-free framework that shifts compression from linear token removal to structure-aware hierarchical selection. BEAVER maximizes hardware parallelism by mapping variable-length contexts into dense page-level tensors via dual-path pooling, and preserves discourse integrity through a hybrid planner combining semantic and lexical dual-branch selection with sentence smoothing. Extensive evaluations on four long-context benchmarks demonstrate that BEAVER achieves comparable performance to state-of-the-art (SOTA) methods like LongLLMLingua. Notably, on the RULER benchmark, BEAVER maintains high fidelity in multi-needle retrieval where baselines deteriorate. Regarding efficiency, BEAVER reduces latency by 26.4x on 128k contexts, offering a scalable solution for high-throughput applications. Our code is available at https://cslikai.cn/BEAVER/.
format Preprint
id arxiv_https___arxiv_org_abs_2603_19635
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle BEAVER: A Training-Free Hierarchical Prompt Compression Method via Structure-Aware Page Selection
Hu, Zhengpei
Li, Kai
Fu, Dapeng
Zeng, Chang
Li, Yue
Tang, Yuanhao
Huang, Jianqiang
Computation and Language
The exponential expansion of context windows in LLMs has unlocked capabilities for long-document understanding but introduced severe bottlenecks in inference latency and information utilization. Existing compression methods often suffer from high training costs or semantic fragmentation due to aggressive token pruning. In this paper, we propose BEAVER, a novel training-free framework that shifts compression from linear token removal to structure-aware hierarchical selection. BEAVER maximizes hardware parallelism by mapping variable-length contexts into dense page-level tensors via dual-path pooling, and preserves discourse integrity through a hybrid planner combining semantic and lexical dual-branch selection with sentence smoothing. Extensive evaluations on four long-context benchmarks demonstrate that BEAVER achieves comparable performance to state-of-the-art (SOTA) methods like LongLLMLingua. Notably, on the RULER benchmark, BEAVER maintains high fidelity in multi-needle retrieval where baselines deteriorate. Regarding efficiency, BEAVER reduces latency by 26.4x on 128k contexts, offering a scalable solution for high-throughput applications. Our code is available at https://cslikai.cn/BEAVER/.
title BEAVER: A Training-Free Hierarchical Prompt Compression Method via Structure-Aware Page Selection
topic Computation and Language
url https://arxiv.org/abs/2603.19635