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Main Authors: Bhardwaj, Asmita, Ong, Yuya Jeremy, Zahid, Eelaaf, Shbita, Basel
Format: Preprint
Published: 2026
Subjects:
Online Access:https://arxiv.org/abs/2603.18428
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author Bhardwaj, Asmita
Ong, Yuya Jeremy
Zahid, Eelaaf
Shbita, Basel
author_facet Bhardwaj, Asmita
Ong, Yuya Jeremy
Zahid, Eelaaf
Shbita, Basel
contents Decoding strategies largely determine the quality of Large Language Model (LLM) outputs, yet widely used heuristics such as greedy or fixed temperature/top-p decoding are static and often task-agnostic, leading to suboptimal or inconsistent generation quality across domains that demand stylistic or structural flexibility. We introduce a reinforcement learning-based decoder sampler that treats decoding as sequential decision-making and learns a lightweight policy to adjust sampling parameters at test-time while keeping LLM weights frozen. We evaluated summarization datasets including BookSum, arXiv, and WikiHow using Granite-3.3-2B and Qwen-2.5-0.5B. Our policy sampler consistently outperforms greedy and static baselines, achieving relative gains of up to +88% (BookSum, Granite) and +79% (WikiHow, Qwen). Reward ablations show that overlap-only objectives underperform compared to composite rewards, while structured shaping terms (length, coverage, repetition, completeness) enable stable and sustained improvements. These findings highlight reinforcement learning as a practical mechanism for test-time adaptation in decoding, enabling domain-aware and user-controllable generation without retraining large models.
format Preprint
id arxiv_https___arxiv_org_abs_2603_18428
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Adaptive Decoding via Test-Time Policy Learning for Self-Improving Generation
Bhardwaj, Asmita
Ong, Yuya Jeremy
Zahid, Eelaaf
Shbita, Basel
Computation and Language
Artificial Intelligence
Decoding strategies largely determine the quality of Large Language Model (LLM) outputs, yet widely used heuristics such as greedy or fixed temperature/top-p decoding are static and often task-agnostic, leading to suboptimal or inconsistent generation quality across domains that demand stylistic or structural flexibility. We introduce a reinforcement learning-based decoder sampler that treats decoding as sequential decision-making and learns a lightweight policy to adjust sampling parameters at test-time while keeping LLM weights frozen. We evaluated summarization datasets including BookSum, arXiv, and WikiHow using Granite-3.3-2B and Qwen-2.5-0.5B. Our policy sampler consistently outperforms greedy and static baselines, achieving relative gains of up to +88% (BookSum, Granite) and +79% (WikiHow, Qwen). Reward ablations show that overlap-only objectives underperform compared to composite rewards, while structured shaping terms (length, coverage, repetition, completeness) enable stable and sustained improvements. These findings highlight reinforcement learning as a practical mechanism for test-time adaptation in decoding, enabling domain-aware and user-controllable generation without retraining large models.
title Adaptive Decoding via Test-Time Policy Learning for Self-Improving Generation
topic Computation and Language
Artificial Intelligence
url https://arxiv.org/abs/2603.18428