Search Results for author: Anru R. Zhang

Found 22 papers, 5 papers with code

Tensor Decomposition Meets RKHS: Efficient Algorithms for Smooth and Misaligned Data

no code implementations11 Aug 2024 Brett W. Larsen, Tamara G. Kolda, Anru R. Zhang, Alex H. Williams

We refer to tensors with some infinite-dimensional modes as quasitensors, and the approach of decomposing a tensor with some continuous RKHS modes is referred to as CP-HiFi (hybrid infinite and finite dimensional) tensor decomposition.

Tensor Decomposition

Reliable Generation of Privacy-preserving Synthetic EHR Time Series via Diffusion Models

1 code implementation23 Oct 2023 Muhang Tian, Bernie Chen, Allan Guo, Shiyi Jiang, Anru R. Zhang

The proposed diffusion-model-based method can reliably and efficiently generate synthetic EHR time series, which facilitates the downstream medical data analysis.

De-identification Denoising +2

Mode-wise Principal Subspace Pursuit and Matrix Spiked Covariance Model

no code implementations2 Jul 2023 Runshi Tang, Ming Yuan, Anru R. Zhang

The MOP-UP algorithm consists of two steps: Average Subspace Capture (ASC) and Alternating Projection (AP).

Phase transition for detecting a small community in a large network

no code implementations9 Mar 2023 Jiashun Jin, Zheng Tracy Ke, Paxton Turner, Anru R. Zhang

Using a degree-corrected block model (DCBM), we establish phase transitions of this testing problem concerning the size of the small community and the edge densities in small and large communities.

Enhancing convolutional neural network generalizability via low-rank weight approximation

no code implementations26 Sep 2022 Chenyin Gao, Shu Yang, Anru R. Zhang

With the proposed design, we are able to characterize our denoiser with fewer parameters and train it based on a single image, which considerably improves the model's generalizability and reduces the cost of data acquisition.

Image Denoising

Sampling is as easy as learning the score: theory for diffusion models with minimal data assumptions

no code implementations22 Sep 2022 Sitan Chen, Sinho Chewi, Jerry Li, Yuanzhi Li, Adil Salim, Anru R. Zhang

We provide theoretical convergence guarantees for score-based generative models (SGMs) such as denoising diffusion probabilistic models (DDPMs), which constitute the backbone of large-scale real-world generative models such as DALL$\cdot$E 2.

Denoising

Tensor-on-Tensor Regression: Riemannian Optimization, Over-parameterization, Statistical-computational Gap, and Their Interplay

1 code implementation17 Jun 2022 Yuetian Luo, Anru R. Zhang

We study the tensor-on-tensor regression, where the goal is to connect tensor responses to tensor covariates with a low Tucker rank parameter tensor/matrix without the prior knowledge of its intrinsic rank.

regression Riemannian optimization

Learning Polynomial Transformations

no code implementations8 Apr 2022 Sitan Chen, Jerry Li, Yuanzhi Li, Anru R. Zhang

Our first main result is a polynomial-time algorithm for learning quadratic transformations of Gaussians in a smoothed setting.

Tensor Decomposition

On Geometric Connections of Embedded and Quotient Geometries in Riemannian Fixed-rank Matrix Optimization

no code implementations23 Oct 2021 Yuetian Luo, Xudong Li, Anru R. Zhang

By applying the general procedure to the fixed-rank positive semidefinite (PSD) and general matrix optimization, we establish an exact Riemannian gradient connection under two geometries at every point on the manifold and sandwich inequalities between the spectra of Riemannian Hessians at Riemannian first-order stationary points (FOSPs).

Riemannian optimization

Nonconvex Factorization and Manifold Formulations are Almost Equivalent in Low-rank Matrix Optimization

no code implementations3 Aug 2021 Yuetian Luo, Xudong Li, Anru R. Zhang

In this paper, we consider the geometric landscape connection of the widely studied manifold and factorization formulations in low-rank positive semidefinite (PSD) and general matrix optimization.

Relation Retrieval

Low-rank Tensor Estimation via Riemannian Gauss-Newton: Statistical Optimality and Second-Order Convergence

1 code implementation24 Apr 2021 Yuetian Luo, Anru R. Zhang

In this paper, we consider the estimation of a low Tucker rank tensor from a number of noisy linear measurements.

regression

Inference for Low-rank Tensors -- No Need to Debias

no code implementations29 Dec 2020 Dong Xia, Anru R. Zhang, Yuchen Zhou

In all these models, we observe that different from many matrix/vector settings in existing work, debiasing is not required to establish the asymptotic distribution of estimates or to make statistical inference on low-rank tensors.

regression

Exact Clustering in Tensor Block Model: Statistical Optimality and Computational Limit

1 code implementation18 Dec 2020 Rungang Han, Yuetian Luo, Miaoyan Wang, Anru R. Zhang

High-order clustering aims to identify heterogeneous substructures in multiway datasets that arise commonly in neuroimaging, genomics, social network studies, etc.

Clustering

Recursive Importance Sketching for Rank Constrained Least Squares: Algorithms and High-order Convergence

no code implementations17 Nov 2020 Yuetian Luo, Wen Huang, Xudong Li, Anru R. Zhang

In this paper, we propose {\it \underline{R}ecursive} {\it \underline{I}mportance} {\it \underline{S}ketching} algorithm for {\it \underline{R}ank} constrained least squares {\it \underline{O}ptimization} (RISRO).

Retrieval

Open Problem: Average-Case Hardness of Hypergraphic Planted Clique Detection

no code implementations12 Sep 2020 Yuetian Luo, Anru R. Zhang

We note the significance of hypergraphic planted clique (HPC) detection in the investigation of computational hardness for a range of tensor problems.

A Sharp Blockwise Tensor Perturbation Bound for Orthogonal Iteration

no code implementations6 Aug 2020 Yuetian Luo, Garvesh Raskutti, Ming Yuan, Anru R. Zhang

Rate matching deterministic lower bound for tensor reconstruction, which demonstrates the optimality of HOOI, is also provided.

Clustering Denoising

Tensor Clustering with Planted Structures: Statistical Optimality and Computational Limits

no code implementations21 May 2020 Yuetian Luo, Anru R. Zhang

We also develop the tight computational thresholds: when the signal-to-noise ratio is below these thresholds, we prove that polynomial-time algorithms cannot solve these problems under the computational hardness conjectures of hypergraphic planted clique (HPC) detection and hypergraphic planted dense subgraph (HPDS) recovery.

Clustering

An Optimal Statistical and Computational Framework for Generalized Tensor Estimation

no code implementations26 Feb 2020 Rungang Han, Rebecca Willett, Anru R. Zhang

Under mild conditions on the loss function, we establish both an upper bound on statistical error and the linear rate of computational convergence through a general deterministic analysis.

Denoising

Sparse Group Lasso: Optimal Sample Complexity, Convergence Rate, and Statistical Inference

no code implementations21 Sep 2019 T. Tony Cai, Anru R. Zhang, Yuchen Zhou

We study sparse group Lasso for high-dimensional double sparse linear regression, where the parameter of interest is simultaneously element-wise and group-wise sparse.

regression

On the Non-asymptotic and Sharp Lower Tail Bounds of Random Variables

no code implementations21 Oct 2018 Anru R. Zhang, Yuchen Zhou

The non-asymptotic tail bounds of random variables play crucial roles in probability, statistics, and machine learning.

Heteroskedastic PCA: Algorithm, Optimality, and Applications

no code implementations19 Oct 2018 Anru R. Zhang, T. Tony Cai, Yihong Wu

A general framework for principal component analysis (PCA) in the presence of heteroskedastic noise is introduced.

Denoising

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