Equivalence of Coarse and Fine-Grained Models for Learning with Distribution Shift

Fuente: arXiv
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Autori principali: Klivans, Adam R., Patel, Shyamal, Stavropoulos, Konstantinos, Vasilyan, Arsen
Natura: Preprint
Pubblicazione: 2026
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author Klivans, Adam R.
Patel, Shyamal
Stavropoulos, Konstantinos
Vasilyan, Arsen
author_facet Klivans, Adam R.
Patel, Shyamal
Stavropoulos, Konstantinos
Vasilyan, Arsen
contents Recent work on provably efficient algorithms for learning with distribution shift has focused on two models: PQ learning (Goldwasser et al. (2020)) and TDS learning (Klivans et al. (2024)). Algorithms for TDS learning are allowed to reject a test set entirely if distribution shift is detected. In contrast, PQ learners may only reject points that are deemed out-of-distribution on an individual basis. Our main result is a surprising equivalence between these two models in the distribution-free setting. In particular, we give an efficient black-box reduction from PQ learning to TDS learning for any Boolean concept class. This equivalence implies the first hardness results for distribution-free TDS learning of basic classes such as halfspaces. The main technical contribution underlying our equivalence is a method for boosting, via branching programs, the weak distinguishing power of TDS learners that have rejected the target domain. We also show that giving a learner access to membership queries sidesteps these hardness results and allows for efficient, distribution-free PQ learnability of halfspaces. Our algorithm iteratively recovers large-margin separators obtained by applying successive Forster transforms on the training data.
format Preprint
id arxiv_https___arxiv_org_abs_2605_07005
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Equivalence of Coarse and Fine-Grained Models for Learning with Distribution Shift
Klivans, Adam R.
Patel, Shyamal
Stavropoulos, Konstantinos
Vasilyan, Arsen
Data Structures and Algorithms
Machine Learning
Recent work on provably efficient algorithms for learning with distribution shift has focused on two models: PQ learning (Goldwasser et al. (2020)) and TDS learning (Klivans et al. (2024)). Algorithms for TDS learning are allowed to reject a test set entirely if distribution shift is detected. In contrast, PQ learners may only reject points that are deemed out-of-distribution on an individual basis. Our main result is a surprising equivalence between these two models in the distribution-free setting. In particular, we give an efficient black-box reduction from PQ learning to TDS learning for any Boolean concept class. This equivalence implies the first hardness results for distribution-free TDS learning of basic classes such as halfspaces. The main technical contribution underlying our equivalence is a method for boosting, via branching programs, the weak distinguishing power of TDS learners that have rejected the target domain. We also show that giving a learner access to membership queries sidesteps these hardness results and allows for efficient, distribution-free PQ learnability of halfspaces. Our algorithm iteratively recovers large-margin separators obtained by applying successive Forster transforms on the training data.
title Equivalence of Coarse and Fine-Grained Models for Learning with Distribution Shift
topic Data Structures and Algorithms
Machine Learning
url https://arxiv.org/abs/2605.07005