ICML Conference 2025 Conference Paper
A Tale of Two Structures: Do LLMs Capture the Fractal Complexity of Language?
- Ibrahim Alabdulmohsin
- Andreas Peter Steiner
Language exhibits a fractal structure in its information-theoretic complexity (i. e. bits per token), with self-similarity across scales and long-range dependence (LRD). In this work, we investigate whether large language models (LLMs) can replicate such fractal characteristics and identify conditions-such as temperature setting and prompting method-under which they may fail. Moreover, we find that the fractal parameters observed in natural language are contained within a narrow range, whereas those of LLMs’ output vary widely, suggesting that fractal parameters might prove helpful in detecting a non-trivial portion of LLM-generated texts. Notably, these findings, and many others reported in this work, are robust to the choice of the architecture; e. g. Gemini 1. 0 Pro, Mistral-7B and Gemma-2B. We also release a dataset comprising over 240, 000 articles generated by various LLMs (both pretrained and instruction-tuned) with different decoding temperatures and prompting methods, along with their corresponding human-generated texts. We hope that this work highlights the complex interplay between fractal properties, prompting, and statistical mimicry in LLMs, offering insights for generating, evaluating and detecting synthetic texts.