arXiv:2605.05566cs.AIcs.CL2026-05

用乱码提示词扰动,让大模型突破复杂问题的思维瓶颈

Nonsense Helps: Prompt Space Perturbation Broadens Reasoning Exploration

论文配图:Nonsense Helps: Prompt Space Perturbation Broadens Reasoning Exploration
图 1 · 摘自论文原文
  • 在提示词前加随机拉丁文伪文本,改变模型输出分布
  • 在1.7B/4B/7B模型上显著提升难任务推理成功率
  • 无需修改模型,适合作为强化学习训练的通用探索增强方法

基于可验证奖励的强化学习,特别是组相对策略优化(GRPO),显著提升了大语言模型(LLM)的推理能力。然而,在复杂任务中,GRPO常面临“零优势问题”:当所有采样轨迹均失败时,相对优势归零,导致模型失去有效训练信号,浪费训练数据和计算资源。尽管增加采样预算是一种常见解决方案,但静态采样策略限制了推理探索范围,难以提升成功率。本文提出Lorem Perturbation for Exploration(LoPE),一种简单有效的训练框架,通过在提示词前随机添加由拉丁文占位符(Lorem Ipsum)组成的序列,实现提示空间扰动,从而改变模型输出分布,解锁针对难题的正交推理路径。在1.7B、4B和7B模型上的实验表明,与原始提示重采样相比,LoPE显著提升性能。进一步分析显示,其他低困惑度的拉丁语系随机序列同样有效。结果证明,LoPE是扩展LLM强化学习探索能力的有力基线。

原文摘要 · Abstract (English)

Reinforcement learning with verifiable rewards, particularly Group Relative Policy Optimization (GRPO), has significantly advanced the reasoning capabilities of Large Language Models (LLMs). However, in complex tasks, GRPO frequently suffers from the ``zero-advantage problem'': when all sampled rollouts for a query fail, the relative advantage collapses to zero. Consequently, the model loses effective training signals for these questions, wasting the training data and computational budget. While simply increasing the sampling budget for these questions is a common remedy, the static sampling policy inherently constrains reasoning exploration, limiting the success rate. In this paper, we propose Lorem Perturbation for Exploration (LoPE), a simple yet effective training framework to break this exploration bottleneck. We posit that task-irrelevant prompt-space perturbations can shift the model's output distribution enough to unlock orthogonal reasoning pathways for hard questions. Specifically, LoPE prepends sequences stochastically assembled from Lorem Ipsum vocabulary (a pseudo-Latin placeholder text) to the prompts before resampling. Experiments across 1.7B, 4B, and 7B models demonstrate that LoPE significantly outperforms resampling with the original prompts. Further analysis reveals that other Latin-based random sequences with low perplexity are also effective perturbations. Our results establish LoPE as a strong baseline for broadening exploration in LLM reinforcement learning.

强化学习提示工程推理增强大模型

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