Consistency of Nonparametric Density Estimators in CAT(0) Orthant Space

Fuente: arXiv
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Main Authors: Takazawa, Yuki, Sei, Tomonari
Format: Preprint
Published: 2025
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_version_ 1866915566298595328
author Takazawa, Yuki
Sei, Tomonari
author_facet Takazawa, Yuki
Sei, Tomonari
contents The inference of evolutionary histories is a central problem in evolutionary biology. The analysis of a sample of phylogenetic trees can be conducted in Billera-Holmes-Vogtmann tree space, which is a CAT(0) metric space of phylogenetic trees. The globally non-positively curved (CAT(0)) property of this space enables the extension of various statistical techniques. In the problem of nonparametric density estimation, two primary methods, kernel density estimation and log-concave maximum likelihood estimation, have been proposed, yet their theoretical properties remain largely unexplored. In this paper, we address this gap by proving the consistency of these estimators in a more general setting$\unicode{x2014}$CAT(0) orthant spaces, which include BHV tree space. We extend log-concave approximation techniques to this setting and establish consistency via the continuity of the log-concave projection map. We also modify the kernel density estimator to correct boundary bias and establish uniform consistency using empirical process theory.
format Preprint
id arxiv_https___arxiv_org_abs_2510_18290
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Consistency of Nonparametric Density Estimators in CAT(0) Orthant Space
Takazawa, Yuki
Sei, Tomonari
Statistics Theory
Methodology
The inference of evolutionary histories is a central problem in evolutionary biology. The analysis of a sample of phylogenetic trees can be conducted in Billera-Holmes-Vogtmann tree space, which is a CAT(0) metric space of phylogenetic trees. The globally non-positively curved (CAT(0)) property of this space enables the extension of various statistical techniques. In the problem of nonparametric density estimation, two primary methods, kernel density estimation and log-concave maximum likelihood estimation, have been proposed, yet their theoretical properties remain largely unexplored. In this paper, we address this gap by proving the consistency of these estimators in a more general setting$\unicode{x2014}$CAT(0) orthant spaces, which include BHV tree space. We extend log-concave approximation techniques to this setting and establish consistency via the continuity of the log-concave projection map. We also modify the kernel density estimator to correct boundary bias and establish uniform consistency using empirical process theory.
title Consistency of Nonparametric Density Estimators in CAT(0) Orthant Space
topic Statistics Theory
Methodology
url https://arxiv.org/abs/2510.18290