arXiv:2503.21073cs.CLcs.LG2025-03被引 35

发现大模型词嵌入具有共享的全局与局部几何结构,可用于跨模型向量转换。

Shared Global and Local Geometry of Language Model Embeddings

  • 分析词嵌入的相对方向与局部线性结构,揭示跨模型几何相似性。
  • 嵌入位于低维流形上,低内在维度的词聚类语义更清晰。
  • 提出EMB2EMB方法,实现不同模型间转向向量的线性转换。

近期研究指出模型可能共享共同表示。本文发现大型语言模型的词嵌入存在大量几何相似性。首先,我们观察到‘全局’相似性:词嵌入常具有相似的相对方向。其次,通过两种方式刻画局部几何:(1) 使用局部线性嵌入(Locally Linear Embeddings),(2) 定义每项嵌入的内在维度简单度量。这两种方法均能发现词嵌入间的局部相似性。此外,内在维度表明嵌入位于低维流形上,内在维度较低的词通常形成语义连贯的簇,而较高者则不然。基于此发现,我们提出EMB2EMB,一种简单的线性变换方法,可将一个语言模型的转向向量映射至另一维度不同的模型。

原文摘要 · Abstract (English)

Researchers have recently suggested that models share common representations. In our work, we find numerous geometric similarities across the token embeddings of large language models. First, we find ``global'' similarities: token embeddings often share similar relative orientations. Next, we characterize local geometry in two ways: (1) by using Locally Linear Embeddings, and (2) by defining a simple measure for the intrinsic dimension of each embedding. Both characterizations allow us to find local similarities across token embeddings. Additionally, our intrinsic dimension demonstrates that embeddings lie on a lower dimensional manifold, and that tokens with lower intrinsic dimensions often have semantically coherent clusters, while those with higher intrinsic dimensions do not. Based on our findings, we introduce EMB2EMB, a simple application to linearly transform steering vectors from one language model to another, despite the two models having different dimensions.

嵌入几何模型对齐词向量

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