Hierarchical Conformal Classification

Fuente: arXiv
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Main Authors: Hengst, Floris den, Blin, Inès, Mohammadi, Majid, Shah, Syed Ihtesham Hussain, Younesian, Taraneh
Format: Preprint
Published: 2025
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author Hengst, Floris den
Blin, Inès
Mohammadi, Majid
Shah, Syed Ihtesham Hussain
Younesian, Taraneh
author_facet Hengst, Floris den
Blin, Inès
Mohammadi, Majid
Shah, Syed Ihtesham Hussain
Younesian, Taraneh
contents Conformal prediction (CP) is a powerful framework for quantifying uncertainty in machine learning models, offering reliable predictions with finite-sample coverage guarantees. When applied to classification, CP produces a prediction set of possible labels that is guaranteed to contain the true label with high probability, regardless of the underlying classifier. However, standard CP treats classes as flat and unstructured, ignoring domain knowledge such as semantic relationships or hierarchical structure among class labels. This paper presents hierarchical conformal classification (HCC), an extension of CP that incorporates class hierarchies into both the structure and semantics of prediction sets. We formulate HCC as a constrained optimization problem whose solutions yield prediction sets composed of nodes at different levels of the hierarchy, while maintaining coverage guarantees. To address the combinatorial nature of the problem, we formally show that a much smaller, well-structured subset of candidate solutions suffices to ensure coverage while upholding optimality. An empirical evaluation on three new benchmarks consisting of audio, image, and text data highlights the advantages of our approach, and a user study shows that annotators significantly prefer hierarchical over flat prediction sets.
format Preprint
id arxiv_https___arxiv_org_abs_2508_13288
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Hierarchical Conformal Classification
Hengst, Floris den
Blin, Inès
Mohammadi, Majid
Shah, Syed Ihtesham Hussain
Younesian, Taraneh
Machine Learning
Artificial Intelligence
Conformal prediction (CP) is a powerful framework for quantifying uncertainty in machine learning models, offering reliable predictions with finite-sample coverage guarantees. When applied to classification, CP produces a prediction set of possible labels that is guaranteed to contain the true label with high probability, regardless of the underlying classifier. However, standard CP treats classes as flat and unstructured, ignoring domain knowledge such as semantic relationships or hierarchical structure among class labels. This paper presents hierarchical conformal classification (HCC), an extension of CP that incorporates class hierarchies into both the structure and semantics of prediction sets. We formulate HCC as a constrained optimization problem whose solutions yield prediction sets composed of nodes at different levels of the hierarchy, while maintaining coverage guarantees. To address the combinatorial nature of the problem, we formally show that a much smaller, well-structured subset of candidate solutions suffices to ensure coverage while upholding optimality. An empirical evaluation on three new benchmarks consisting of audio, image, and text data highlights the advantages of our approach, and a user study shows that annotators significantly prefer hierarchical over flat prediction sets.
title Hierarchical Conformal Classification
topic Machine Learning
Artificial Intelligence
url https://arxiv.org/abs/2508.13288