用黎曼几何统一非线性语言模型操控,无需标签即可精准引导。
Riemannian-Manifold Steering: Geometry-Aware Generative Autoencoders for Label-Free Steering

- 将激活空间的操纵建模为黎曼测地线计算,统一多种干预方法。
- 在四任务语言模型算术基准上,全任务准确率达100%且轨迹更自然。
- 仅需少量概念词模板,无须标签、拓扑先验或路径拟合,适合通用场景。
语言模型的操纵(steering)近年从线性插值扩展至非线性方法,如角度和核化操纵,这些方法不显式学习激活空间路径的几何结构。新提出的几何感知流形方法虽学习了该几何,但依赖标注类别中心点及预设循环或序列结构,限制了应用范围。本文将流形操纵重新表述为激活空间上的黎曼测地线计算,使线性和标注样条操纵成为特定度量下的测地线。提出一种基于输出空间赫林格距离回传至激活空间的合理度量,并通过小规模概念-词模板训练的编码器近似实现;无需每提示标签、无拓扑先验,也无需任务特异性曲线拟合。实验表明,该方法在标准四任务语言模型算术基准中,所有任务均可靠地引导至目标类别,且在较小输出空间下轨迹更符合行为逻辑。由此提供了一个统一的黎曼框架,以及一个基于模式监督、无需标签的实例化方案,无需标注中心点或预设边界条件。
原文摘要 · Abstract (English)
Steering a language model - intervening on its internal activations to change downstream behaviour - has recently expanded beyond linear interpolation to nonlinear methods such as angular and kernelized steering, which define intervention transformations without learning an explicit geometry over paths in activation space. Freshly introduced geometry-aware manifold methods do learn such a geometry, but require labelled class centroids together with prescribed cyclic or sequential structure. These assumptions restrict where manifold steering can be applied, since existing constructions require labelled centroids and compatible boundary conditions. We recast manifold steering more broadly as \textbf{Riemannian geodesic computation} on activation space, recovering linear and labelled-spline steering as geodesics under particular choices of metric. A principled metric within this framework is the output-space Hellinger distance pulled back to activations; we approximate this with a learned encoder trained on output distances over a small concept-token schema - no per-prompt labels, no topology prior, and no per-task curve fitting. Empirically, the method reliably drives the model onto the target class across all tasks in a standard four-task language-model arithmetic benchmark, while following more behaviourally natural trajectories than baselines on smaller output spaces. We thereby provide a unified Riemannian framework for manifold steering together with a schema-supervised, label-free instantiation that operates without labelled centroids or prescribed boundary conditions.
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