arXiv Machine Learning
Jul 14

Demixing Sparse Signals from Nonlinear Observations using Generalized Non-convex Regularization

arXiv:2607. 10618v1 Announce Type: cross Abstract: We consider the recovery of a pair of sparse vectors from a limited number of nonlinear observations of their superposition: $y_i=g(\inner{\ba_i}{\bPhi\bw^\ast+\bPsi\bz^\ast})+e_i$, $i=1,\dots,m$, with $m\ll n$, incoherent orthonormal bases $\bPhi,\bPsi$, a scalar link $g$, and noise $e_i$ that may be heavy-tailed or contaminated.

By Raziyeh Takbiri
arXiv Machine Learning
Sep 4

Restricted Eigenvalues Beyond Gaussian Width: Threshold Occupancy under Heavy Tails

The paper investigates restricted eigenvalue (RE) bounds for norm‑regularized estimators under heavy‑tailed designs. It shows that the previously conjectured sample‑size law based on Gaussian width fails for heavy‑tailed measurements, due to a phenomenon called simultaneous threshold occupancy. The authors provide explicit counterexamples, derive worst‑case sample‑complexity bounds, and compare the behavior of heavy‑tailed versus Gaussian designs on constant‑width polyhedral descent cones.

By Shi Fu, Huibo Xu, Qixin Zhang, Dacheng Tao
arXiv Machine Learning
Oct 19

Distinguishability and Recovery for a Doubly Sparse Spiked Wigner Model

The paper investigates how to distinguish and recover a sparse rank‑one signal in a spiked Wigner model where both the signal and the noise are independently sparse. It introduces a leave‑one‑out quadratic thresholding method that identifies the signal support for sub‑Gaussian noise and bounded spikes, and shows that sign synchronization and spectral refinement can achieve exact or strong recovery for Rademacher spikes. The work also extends to sub‑Gaussian spike priors, provides an explicit trade‑off between signal sparsity, noise sparsity, and computational cost, and establishes recoverability conditions that do not rely on moment assumptions for continuous noise.

By Ioana Dumitriu, JD Flynn, Zhichao Wang