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Main Authors: Pang, Lingyou, Huang, Lei, Lin, Jianyu, Wang, Tianyu, Horiguchi, Akira, Aue, Alexander, Priebe, Carey E.
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2509.23002
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author Pang, Lingyou
Huang, Lei
Lin, Jianyu
Wang, Tianyu
Horiguchi, Akira
Aue, Alexander
Priebe, Carey E.
author_facet Pang, Lingyou
Huang, Lei
Lin, Jianyu
Wang, Tianyu
Horiguchi, Akira
Aue, Alexander
Priebe, Carey E.
contents Deploying black-box LLMs requires managing uncertainty in the absence of token-level probability or true labels. We propose introducing an unsupervised conformal inference framework for generation, which integrates: generative models, incorporating: (i) an LLM-compatible atypical score derived from response-embedding Gram matrix, (ii) UCP combined with a bootstrapping variant (BB-UCP) that aggregates residuals to refine quantile precision while maintaining distribution-free, finite-sample coverage, and (iii) conformal alignment, which calibrates a single strictness parameter $τ$ so a user predicate (e.g., factuality lift) holds on unseen batches with probability $\ge 1-α$. Across different benchmark datasets, our gates achieve close-to-nominal coverage and provide tighter, more stable thresholds than split UCP, while consistently reducing the severity of hallucination, outperforming lightweight per-response detectors with similar computational demands. The result is a label-free, API-compatible gate for test-time filtering that turns geometric signals into calibrated, goal-aligned decisions.
format Preprint
id arxiv_https___arxiv_org_abs_2509_23002
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Unsupervised Conformal Inference: Bootstrapping and Alignment to Control LLM Uncertainty
Pang, Lingyou
Huang, Lei
Lin, Jianyu
Wang, Tianyu
Horiguchi, Akira
Aue, Alexander
Priebe, Carey E.
Machine Learning
Deploying black-box LLMs requires managing uncertainty in the absence of token-level probability or true labels. We propose introducing an unsupervised conformal inference framework for generation, which integrates: generative models, incorporating: (i) an LLM-compatible atypical score derived from response-embedding Gram matrix, (ii) UCP combined with a bootstrapping variant (BB-UCP) that aggregates residuals to refine quantile precision while maintaining distribution-free, finite-sample coverage, and (iii) conformal alignment, which calibrates a single strictness parameter $τ$ so a user predicate (e.g., factuality lift) holds on unseen batches with probability $\ge 1-α$. Across different benchmark datasets, our gates achieve close-to-nominal coverage and provide tighter, more stable thresholds than split UCP, while consistently reducing the severity of hallucination, outperforming lightweight per-response detectors with similar computational demands. The result is a label-free, API-compatible gate for test-time filtering that turns geometric signals into calibrated, goal-aligned decisions.
title Unsupervised Conformal Inference: Bootstrapping and Alignment to Control LLM Uncertainty
topic Machine Learning
url https://arxiv.org/abs/2509.23002