arXiv Machine Learning

Metric Conformal Prediction via the Conditional Expected Local Radius

The paper introduces the conditional expected local radius (CELR), a new tool for measuring local conditional probability concentration in general metric spaces. Using CELR, the authors develop a conformal prediction method that works for non‑Euclidean responses, accommodates heterogeneity and multimodality without requiring densities or vector‑space structure, and avoids costly transport comparisons. The method is implemented via a metric distributional random forest that handles multivariate covariates and nonlinear interactions, yielding uniform consistency, asymptotic conditional validity, and finite‑sample marginal coverage under exchangeability, while also providing substantial computational savings compared to existing approaches.

arXiv Machine Learning
Jun 11

Projected random forests and conformal prediction of circular data

arXiv:2410. 24145v3 Announce Type: replace-cross Abstract: We apply conformal prediction techniques to regression problems with circular responses, producing prediction sets with adaptive arc length and finite-sample coverage guarantees for any circular predictive model under the assumption of data exchangeability.

By Paulo C. Marques F., Rinaldo Artes, Helton Graziadei
arXiv Machine Learning
Aug 7

Beyond Marginal Validity: Finite-Sample Guarantees for Localized Conformal Prediction

arXiv:2608. 06206v1 Announce Type: cross Abstract: Conformal prediction endows arbitrary black-box predictors with finite-sample, distribution-free marginal coverage, yet marginal validity can hide severe covariate-specific miscalibration, while exact distribution-free conditional coverage is finite-sample unattainable.

By Anton Conrad, Rustam Isaev, Denis Belomestny, Eric Moulines, Sergey Samsonov
arXiv Machine Learning
Sep 11

Benchmarking non-conformity score functions in conformal prediction

Conformal prediction replaces single-class predictions with prediction sets that guarantee a pre-specified coverage probability. The paper reviews properties of non‑conformity score functions, presents examples from the literature, and proposes new modifications. It introduces a method to evaluate prediction set sizes and compares different score functions, including their effectiveness for class‑conditional conformal prediction with imbalanced classes.

By Sol Erika Boman
arXiv Machine Learning
Jun 18

Kernel of Partition Paths: A Unified Representation for Tree Ensembles

arXiv:2606. 18853v1 Announce Type: cross Abstract: A recent line of work has reframed individual decision trees as linear models on engineered features associated with their splits, opening routes for oracle inequalities and feature-importance reinterpretation, but leaving open the question of what unified geometric object a forest induces when one indexes its feature map by nodes rather than by splits.

By Nicolas Mahler
arXiv Machine Learning
Oct 19

Adaptive conformal prediction on the Grassmannian

The paper presents a conformal prediction framework for regression problems where the responses lie on the Grassmann manifold. It builds prediction regions as metric balls on the manifold, using basis‑invariant geometric distances as non‑conformity measures and scaling them with a learned prediction‑difficulty estimator to achieve locally adaptive, input‑dependent regions. The method preserves finite‑sample marginal coverage under exchangeability and is evaluated on synthetic data and an airfoil inverse shape‑design task, showing that geometry‑aware scores and local adaptation improve coverage uniformity and can reduce region size in heteroscedastic settings.

By Dimitrios Loukrezis, Zachary J. Grey, Dimitris G. Giovanis