A note on the impossibility of conditional PAC-efficient reasoning in large language models

Fuente: arXiv
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Main Author: Zeng, Hao
Format: Preprint
Published: 2025
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author Zeng, Hao
author_facet Zeng, Hao
contents We prove an impossibility result for conditional Probably Approximately Correct (PAC)-efficient reasoning in large language models. While recent work has established marginal PAC efficiency guarantees for composite models that switch between expensive expert models and cheaper fast models, we show that conditional (pointwise) guarantees are impossible in the distribution-free setting. Specifically, for non-atomic input spaces, any algorithm achieving conditional PAC efficiency must be trivial in the sense that it defers to the expert model with probability at least $1-α$ for almost every input.
format Preprint
id arxiv_https___arxiv_org_abs_2512_03057
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle A note on the impossibility of conditional PAC-efficient reasoning in large language models
Zeng, Hao
Machine Learning
Artificial Intelligence
Statistics Theory
We prove an impossibility result for conditional Probably Approximately Correct (PAC)-efficient reasoning in large language models. While recent work has established marginal PAC efficiency guarantees for composite models that switch between expensive expert models and cheaper fast models, we show that conditional (pointwise) guarantees are impossible in the distribution-free setting. Specifically, for non-atomic input spaces, any algorithm achieving conditional PAC efficiency must be trivial in the sense that it defers to the expert model with probability at least $1-α$ for almost every input.
title A note on the impossibility of conditional PAC-efficient reasoning in large language models
topic Machine Learning
Artificial Intelligence
Statistics Theory
url https://arxiv.org/abs/2512.03057