A 1/R Law for Kurtosis Contrast in Balanced Mixtures

Fuente: arXiv
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Auteurs principaux: Bi, Yuda, Xiao, Wenjun, Bai, Linhao, Calhoun, Vince D
Format: Preprint
Publié: 2026
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author Bi, Yuda
Xiao, Wenjun
Bai, Linhao
Calhoun, Vince D
author_facet Bi, Yuda
Xiao, Wenjun
Bai, Linhao
Calhoun, Vince D
contents Kurtosis-based Independent Component Analysis (ICA) weakens in wide, balanced mixtures. We prove a sharp redundancy law: for a standardized projection with effective width $R_{\mathrm{eff}}$ (participation ratio), the population excess kurtosis obeys $|κ(y)|=O(κ_{\max}/R_{\mathrm{eff}})$, yielding the order-tight $O(c_bκ_{\max}/R)$ under balance (typically $c_b=O(\log R)$). As an impossibility screen, under standard finite-moment conditions for sample kurtosis estimation, surpassing the $O(1/\sqrt{T})$ estimation scale requires $R\lesssim κ_{\max}\sqrt{T}$. We also show that \emph{purification} -- selecting $m\!\ll\!R$ sign-consistent sources -- restores $R$-independent contrast $Ω(1/m)$, with a simple data-driven heuristic. Synthetic experiments validate the predicted decay, the $\sqrt{T}$ crossover, and contrast recovery.
format Preprint
id arxiv_https___arxiv_org_abs_2602_22334
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle A 1/R Law for Kurtosis Contrast in Balanced Mixtures
Bi, Yuda
Xiao, Wenjun
Bai, Linhao
Calhoun, Vince D
Machine Learning
Artificial Intelligence
Kurtosis-based Independent Component Analysis (ICA) weakens in wide, balanced mixtures. We prove a sharp redundancy law: for a standardized projection with effective width $R_{\mathrm{eff}}$ (participation ratio), the population excess kurtosis obeys $|κ(y)|=O(κ_{\max}/R_{\mathrm{eff}})$, yielding the order-tight $O(c_bκ_{\max}/R)$ under balance (typically $c_b=O(\log R)$). As an impossibility screen, under standard finite-moment conditions for sample kurtosis estimation, surpassing the $O(1/\sqrt{T})$ estimation scale requires $R\lesssim κ_{\max}\sqrt{T}$. We also show that \emph{purification} -- selecting $m\!\ll\!R$ sign-consistent sources -- restores $R$-independent contrast $Ω(1/m)$, with a simple data-driven heuristic. Synthetic experiments validate the predicted decay, the $\sqrt{T}$ crossover, and contrast recovery.
title A 1/R Law for Kurtosis Contrast in Balanced Mixtures
topic Machine Learning
Artificial Intelligence
url https://arxiv.org/abs/2602.22334