activity
20232026
most citedCovariance Operator Estimation: Sparsity, Lengthscale, and Ensemble Kalman Filters

2 citations · 3 across the 12 of their papers we have counts for

collaborators

13 papers

cs.DS2026

A Simpler Analysis of the Bansal-Jiang Quasi Monte-Carlo Algorithm via Haar Wavelets

Jiaheng Chen, Agastya Vibhuti Jha, Haotian Jiang

Numerical integration---approximating the integral of a function using point evaluations---is a central task in science and engineering. The two main paradigms for this pro…

math.PR2026

Sharp Frobenius-Norm Concentration for Sample Moment Tensors

Jiaheng Chen, Daniel Sanz-Alonso

This paper establishes sharp dimension-free Frobenius-norm concentration inequalities for sample moment tensors. Our bounds are optimal over the sub-Gaussian class, while for Gauss…

math.PR2026

Concentration Inequalities for Sample Cross-Covariances

Jiaheng Chen, Daniel Sanz-Alonso

This paper establishes sharp dimension-free concentration and expectation bounds for the deviation of a sample cross-covariance matrix from its mean. For sub-Gaussian random vector…

math.OC2026

A Homogeneous Second-Order Descent Ascent Algorithm for Nonconvex-Strongly Concave Minimax Problems

Jia-Hao Chen, Zi Xu, Hui-Ling Zhang

This paper introduces a novel Homogeneous Second-order Descent Ascent (HSDA) algorithm for nonconvex-strongly concave minimax optimization problems. At each iteration, HSDA uniquel…

math.ST2026

Convergence Rates for Learning Pseudo-Differential Operators

Jiaheng Chen, Daniel Sanz-Alonso

This paper establishes convergence rates for learning elliptic pseudo-differential operators, a fundamental operator class in partial differential equations and mathematical physic…

math.NA2025

High-Dimensional Quasi-Monte Carlo via Combinatorial Discrepancy

Jiaheng Chen, Haotian Jiang, Nathan Kirk

Monte Carlo (MC) and Quasi-Monte Carlo (QMC) methods are classical approaches for the numerical integration of functions over . While QMC methods can achieve faster co…

math.ST2025

On the Estimation of Gaussian Moment Tensors

Omar Al-Ghattas, Jiaheng Chen, Daniel Sanz-Alonso

This paper studies two estimators for Gaussian moment tensors: the standard sample moment estimator and a plug-in estimator based on Isserlis's theorem. We establish dimension-free…

math.PR2025

Sharp Concentration of Simple Random Tensors II: Asymmetry

Jiaheng Chen, Daniel Sanz-Alonso

This paper establishes sharp concentration inequalities for simple random tensors. Our theory unveils a phenomenon that arises only for asymmetric tensors of order when…

cs.LG2025

VAMO: Efficient Zeroth-Order Variance Reduction for SGD with Faster Convergence

Jiahe Chen, Ziye Ma

Optimizing large-scale nonconvex problems, common in deep learning, demands balancing rapid convergence with computational efficiency. First-order (FO) optimizers, which serve as t…

math.PR2025

Sharp Concentration of Simple Random Tensors

Omar Al-Ghattas, Jiaheng Chen, Daniel Sanz-Alonso

This paper establishes sharp dimension-free concentration inequalities and expectation bounds for the deviation of the sum of simple random tensors from its expectation. As part of…

math.ST2024

Precision and Cholesky Factor Estimation for Gaussian Processes

Jiaheng Chen, Daniel Sanz-Alonso

This paper studies the estimation of large precision matrices and Cholesky factors obtained by observing a Gaussian process at many locations. Under general assumptions on the prec…

math.ST2024★ 1 cited

Optimal Estimation of Structured Covariance Operators

Omar Al-Ghattas, Jiaheng Chen, Daniel Sanz-Alonso +1

This paper establishes optimal convergence rates for estimation of structured covariance operators of Gaussian processes. We study banded operators with kernels that decay rapidly…

math.ST2023★ 2 cited

Covariance Operator Estimation: Sparsity, Lengthscale, and Ensemble Kalman Filters

Omar Al-Ghattas, Jiaheng Chen, Daniel Sanz-Alonso +1

This paper investigates covariance operator estimation via thresholding. For Gaussian random fields with approximately sparse covariance operators, we establish non-asymptotic boun…