In plain words: They measured the shape of the word-piece space inside three open language models — its size and how sharply it bends. It is layered rather than one smooth surface, with each layer strongly curved, and these measures tracked how fluently the models write.
Abstract
Large language models encode the correlational structure present in natural language by fitting segments of utterances (tokens) into a high dimensional ambient latent space upon which the models then operate. We assert that in order to develop a foundational, first-principles understanding of the behavior and limitations of large language models, it is crucial to understand the topological and geometric structure of this token subspace. In this article, we present estimators for the dimension and Ricci scalar curvature of the token subspace, and apply it to three open source large language models of moderate size: GPT2, LLEMMA7B, and MISTRAL7B. In all three models, using these measurements, we find that the token subspace is not a manifold, but is instead a stratified manifold, where on each of the individual strata, the Ricci curvature is significantly negative. We additionally find that the dimension and curvature correlate with generative fluency of the models, which suggest that these findings have implications for model behavior.
Michael Robinson, Sourya Dey, Shauna Sweet
arXiv:2410.08993 · math.DG, cs.AI · submitted Oct 11, 2024
abstract · pdf · html · 33 pages, 22 figures