用随机矩阵理论分析大模型内部结构,提升可靠性与效率。
Structure and Redundancy in Large Language Models: A Spectral Study via Random Matrix Theory
- 通过谱分析捕捉隐藏层激活的统计规律,识别有效信号与噪声。
- 提出EigenTrack实时检测幻觉和分布外样本,准确率显著提升。
- RMT-KD压缩模型时保留关键信息,实现高效低耗部署。
本论文针对深度学习中日益突出的可靠性与效率问题,构建基于谱几何与随机矩阵理论(RMT)的统一框架。随着大模型规模扩大,其内部行为变得愈发不可解释,导致幻觉、分布偏移下泛化能力脆弱以及计算与能耗上升。通过分析各层与输入下隐藏激活的特征值动态,研究发现谱统计具有紧凑、稳定且可解释的优势,能够区分结构化因果表示与噪声主导的波动。首个贡献EigenTrack提出一种实时方法,用于检测大语言模型与视觉语言模型中的幻觉及分布外行为:将流式激活转化为熵、方差及偏离Marchenko-Pastur基线的谱描述符,并用轻量级循环分类器建模其时间演化,在输出异常前实现早期可靠度故障预警,同时提供表示动态的可解释性洞察。第二个贡献RMT-KD提出基于随机矩阵理论的知识蒸馏压缩方法:将激活谱中的异常特征值视为任务相关信源,通过迭代自蒸馏逐步将网络投影至低维子空间,生成更紧凑、节能且硬件友好的模型,同时保持高精度与密集结构。
原文摘要 · Abstract (English)
This thesis addresses two persistent and closely related challenges in modern deep learning, reliability and efficiency, through a unified framework grounded in Spectral Geometry and Random Matrix Theory (RMT). As deep networks and large language models continue to scale, their internal behavior becomes increasingly opaque, leading to hallucinations, fragile generalization under distribution shift, and growing computational and energy demands. By analyzing the eigenvalue dynamics of hidden activations across layers and inputs, this work shows that spectral statistics provide a compact, stable, and interpretable lens on model behavior, capable of separating structured, causal representations from noise-dominated variability. Within this framework, the first contribution, EigenTrack, introduces a real-time method for detecting hallucinations and out-of-distribution behavior in large language and vision-language models. EigenTrack transforms streaming activations into spectral descriptors such as entropy, variance, and deviations from the Marchenko-Pastur baseline, and models their temporal evolution using lightweight recurrent classifiers, enabling early detection of reliability failures before they appear in model outputs while offering interpretable insight into representation dynamics. The second contribution, RMT-KD, presents a principled approach to compressing deep networks via random matrix theoretic knowledge distillation. By interpreting outlier eigenvalues in activation spectra as carriers of task-relevant information, RMT-KD progressively projects networks onto lower-dimensional subspaces through iterative self-distillation, yielding significantly more compact and energy-efficient models while preserving accuracy and dense, hardware-friendly structure.
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