Density-Ratio Losses for Post-Hoc Learning to Defer

Fuente: arXiv
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Main Authors: Soen, Alexander, Thobaben, Ragnar, Jaldén, Joakim, Nock, Richard
Format: Preprint
Published: 2026
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author Soen, Alexander
Thobaben, Ragnar
Jaldén, Joakim
Nock, Richard
author_facet Soen, Alexander
Thobaben, Ragnar
Jaldén, Joakim
Nock, Richard
contents We study post-hoc Learning to Defer (L2D) through the lens of ideal distributions: divergence-regularized reweightings of the data distribution under which a model attains low loss. We define deferral via the density-ratio between a model's and an expert's ideals. Using the reduction from density-ratio estimation to class-probability estimation, we derive the DR CPE losses for post-hoc L2D scorers. Deferral decisions are then made by thresholding the scorer, allowing deferral rates to be adjusted without retraining. For KL-based ideal distributions, our deferral rules recovers Chow's rule under the original distribution and a connection to an expert-tilted Bayes posterior -- which incorporates the expert's performance -- depending on if the ideal distributions are joint or marginal distributions. Experimentally, our approach is competitive compared to common baselines and more robust across dataset settings. More broadly, our results cast post-hoc L2D as density-ratio learning between ideal distributions, bridging Chow-style rules, expert comparison, and elucidating connections to related learning settings including anomaly detection.
format Preprint
id arxiv_https___arxiv_org_abs_2605_19557
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Density-Ratio Losses for Post-Hoc Learning to Defer
Soen, Alexander
Thobaben, Ragnar
Jaldén, Joakim
Nock, Richard
Machine Learning
We study post-hoc Learning to Defer (L2D) through the lens of ideal distributions: divergence-regularized reweightings of the data distribution under which a model attains low loss. We define deferral via the density-ratio between a model's and an expert's ideals. Using the reduction from density-ratio estimation to class-probability estimation, we derive the DR CPE losses for post-hoc L2D scorers. Deferral decisions are then made by thresholding the scorer, allowing deferral rates to be adjusted without retraining. For KL-based ideal distributions, our deferral rules recovers Chow's rule under the original distribution and a connection to an expert-tilted Bayes posterior -- which incorporates the expert's performance -- depending on if the ideal distributions are joint or marginal distributions. Experimentally, our approach is competitive compared to common baselines and more robust across dataset settings. More broadly, our results cast post-hoc L2D as density-ratio learning between ideal distributions, bridging Chow-style rules, expert comparison, and elucidating connections to related learning settings including anomaly detection.
title Density-Ratio Losses for Post-Hoc Learning to Defer
topic Machine Learning
url https://arxiv.org/abs/2605.19557