Correlation Dimension of Auto-Regressive Large Language Models

Fuente: arXiv
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Main Authors: Du, Xin, Tanaka-Ishii, Kumiko
Format: Preprint
Published: 2025
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author Du, Xin
Tanaka-Ishii, Kumiko
author_facet Du, Xin
Tanaka-Ishii, Kumiko
contents Large language models (LLMs) have achieved remarkable progress in natural language generation, yet they continue to display puzzling behaviors -- such as repetition and incoherence -- even when exhibiting low perplexity. This highlights a key limitation of conventional evaluation metrics, which emphasize local prediction accuracy while overlooking long-range structural complexity. We introduce correlation dimension, a fractal-geometric measure of self-similarity, to quantify the epistemological complexity of text as perceived by a language model. This measure captures the hierarchical recurrence structure of language, bridging local and global properties in a unified framework. Through extensive experiments, we show that correlation dimension (1) reveals three distinct phases during pretraining, (2) reflects context-dependent complexity, (3) indicates a model's tendency toward hallucination, and (4) reliably detects multiple forms of degeneration in generated text. The method is computationally efficient, robust to model quantization (down to 4-bit precision), broadly applicable across autoregressive architectures (e.g., Transformer and Mamba), and provides fresh insight into the generative dynamics of LLMs.
format Preprint
id arxiv_https___arxiv_org_abs_2510_21258
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Correlation Dimension of Auto-Regressive Large Language Models
Du, Xin
Tanaka-Ishii, Kumiko
Computation and Language
Artificial Intelligence
Chaotic Dynamics
Large language models (LLMs) have achieved remarkable progress in natural language generation, yet they continue to display puzzling behaviors -- such as repetition and incoherence -- even when exhibiting low perplexity. This highlights a key limitation of conventional evaluation metrics, which emphasize local prediction accuracy while overlooking long-range structural complexity. We introduce correlation dimension, a fractal-geometric measure of self-similarity, to quantify the epistemological complexity of text as perceived by a language model. This measure captures the hierarchical recurrence structure of language, bridging local and global properties in a unified framework. Through extensive experiments, we show that correlation dimension (1) reveals three distinct phases during pretraining, (2) reflects context-dependent complexity, (3) indicates a model's tendency toward hallucination, and (4) reliably detects multiple forms of degeneration in generated text. The method is computationally efficient, robust to model quantization (down to 4-bit precision), broadly applicable across autoregressive architectures (e.g., Transformer and Mamba), and provides fresh insight into the generative dynamics of LLMs.
title Correlation Dimension of Auto-Regressive Large Language Models
topic Computation and Language
Artificial Intelligence
Chaotic Dynamics
url https://arxiv.org/abs/2510.21258