Gradient Descent Dynamics of Rank-One Matrix Denoising

ICLR 2026 Conference SubmissionAnonymous Authors
Random Matrix TheoryHigh-Dimensional StatisticsMatrix DenoisingGradient Flow
Abstract:

Matrix denoising is a crucial component in machine learning, offering valuable insights into the behavior of learning algorithms (Bishop and Nasrabadi, 2006). This paper focuses on the rectangular matrix denoising problem, which involves estimating the left and right singular vectors of a rank-one matrix that is corrupted by additive noise. Traditional algorithms for this problem often exhibit high computational complexity, leading to the widespread use of gradient descent (GD)-based estimation methods with a quadratic cost function. However, the learning dynamics of these GD-based methods, particularly the analytical solutions that describe their exact trajectories, have been largely overlooked in existing literature. To fill this gap, we investigate the learning dynamics in detail, providing convergence proofs and asymptotic analysis. By leveraging tools from large random matrix theory, we derive a closed-form solution for the learning dynamics, characterized by the inner products of the estimates and the ground truth vectors. We rigorously prove the almost sure convergence of these dynamics as the signal dimensions tend to infinity. Additionally, we analyze the asymptotic behavior of the learning dynamics in the large-time limit, which aligns with the well-known Baik-Ben Arous-Péchée phase transition phenomenon n (Baik et al., 2005). Experimental results support our theoretical findings, demonstrating that when the signal-to-noise ratio (SNR) surpasses a critical threshold, learning converges rapidly from an initial value close to the stationary point. In contrast, estimation becomes infeasible when the ratio of the inner products between the initial left and right vectors and their corresponding ground truth vectors reaches a specific value, which depends on both the SNR and the data dimensions.

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Overview

Overall Novelty Assessment

The paper derives closed-form solutions for gradient descent dynamics in rank-one matrix denoising, providing convergence proofs and asymptotic analysis using random matrix theory. It resides in the 'Rank-One Matrix Estimation Dynamics' leaf, which contains only three papers total, indicating a relatively sparse research direction within the broader taxonomy. This leaf focuses specifically on gradient trajectories for rank-one recovery from noisy observations, distinguishing it from general low-rank methods or algorithmic design without theoretical dynamics analysis.

The taxonomy reveals that neighboring leaves address related but distinct concerns: 'Low-Rank Fine-Tuning and Perturbation Dynamics' examines gradient behavior when perturbing pre-trained models rather than de novo recovery, while 'Noise Regularization and Implicit Bias' investigates how noise in gradient updates induces regularization effects. The broader 'Gradient Descent Dynamics and Convergence Analysis' branch contains four leaves spanning rank-one estimation, manifold optimization, and noise-induced regularization, suggesting the paper sits at the intersection of optimization theory and statistical recovery but within a narrowly defined problem class.

Among thirty candidates examined, the first contribution (closed-form dynamics) shows two refutable candidates from ten examined, while the second contribution (convergence proof) has one refutable candidate from ten. The third contribution (BBP-like phase transition with signed result) appears more novel, with zero refutable candidates among ten examined. These statistics suggest that while deterministic approximations and convergence analysis have some prior coverage in the limited search scope, the specific asymptotic phase transition characterization may represent a less-explored aspect of rank-one denoising dynamics.

Based on the top-thirty semantic matches examined, the work appears to occupy a specialized niche within gradient descent theory for low-rank problems. The sparse taxonomy leaf and mixed refutability statistics indicate moderate novelty, though the limited search scope means substantial related work outside the candidate set cannot be ruled out. The phase transition analysis stands out as the contribution with least apparent prior overlap in this search.

Taxonomy

Core-task Taxonomy Papers
38
3
Claimed Contributions
30
Contribution Candidate Papers Compared
3
Refutable Paper

Research Landscape Overview

Core task: gradient descent dynamics of rank-one matrix denoising. The field encompasses a broad spectrum of approaches to recovering low-rank structure from noisy observations, organized into several major branches. Gradient Descent Dynamics and Convergence Analysis investigates how iterative optimization evolves over time, examining convergence guarantees and the trajectory of gradient-based methods applied to rank-constrained problems. Algorithm Design and Optimization Methods focuses on developing practical solvers—ranging from nonnegative matrix factorization variants like Conic NMF Algorithms[4] and Manhattan NMF[6] to specialized techniques for structured factorizations. Noise Modeling and Robustness addresses how different noise regimes and perturbations affect recovery, while Theoretical Foundations and Optimality establishes fundamental limits and landscape geometry, as seen in works like Low-Rank Optimization Geometry[2] and Nonconvex Low-Rank Overview[3]. Application-Driven Methods tailors these ideas to domains such as hyperspectral imaging, channel estimation, and crowdsourcing. Within the dynamics and convergence branch, a particularly active line of work examines how gradient descent behaves on rank-one estimation problems under various noise models and initialization schemes. Rank-One Denoising Dynamics[0] sits squarely in this cluster, analyzing the fine-grained temporal evolution of gradient descent for rank-one matrix recovery. It shares thematic ties with Rank-One Time Evolution[20], which similarly studies dynamical trajectories, and Constrained Rank-One Estimation[22], which explores estimation under additional constraints. Compared to broader surveys like Nonconvex Low-Rank Overview[3] that cover landscape geometry across many problem classes, Rank-One Denoising Dynamics[0] zooms in on the specific interplay between noise structure and optimization paths in the rank-one regime. This focus complements works on initialization strategies such as Rank-One Random Initialization[9] and robustness studies like Noise Regularizes Rank-One[10], collectively illuminating how algorithmic choices and noise characteristics shape convergence in low-rank denoising.

Claimed Contributions

Closed-form deterministic approximations for gradient descent learning dynamics

The authors obtain deterministic approximations in closed form for the evolution of inner products between learned vectors and ground truth in rank-one matrix denoising. These approximations are expressed via integrals over the Marčenko-Pastur measure and basis functions involving hyperbolic trigonometric terms.

10 retrieved papers
Can Refute
Almost sure convergence proof for high-dimensional learning dynamics

The authors rigorously prove that as the dimensions of the observation matrix approach infinity, the empirical evolution processes converge almost surely to the deterministic approximations. This result leverages large random matrix theory tools and establishes strong convergence guarantees.

10 retrieved papers
Can Refute
Asymptotic analysis revealing BBP-like phase transition with signed result

The authors investigate the large-time limit of the learning dynamics and show a phase transition analogous to the BBP phenomenon. Unlike the unsigned BBP result concerning squared inner products, they derive a signed result that depends on initial conditions and the signal-to-noise ratio.

10 retrieved papers

Core Task Comparisons

Comparisons with papers in the same taxonomy category

Contribution Analysis

Detailed comparisons for each claimed contribution

Contribution

Closed-form deterministic approximations for gradient descent learning dynamics

The authors obtain deterministic approximations in closed form for the evolution of inner products between learned vectors and ground truth in rank-one matrix denoising. These approximations are expressed via integrals over the Marčenko-Pastur measure and basis functions involving hyperbolic trigonometric terms.

Contribution

Almost sure convergence proof for high-dimensional learning dynamics

The authors rigorously prove that as the dimensions of the observation matrix approach infinity, the empirical evolution processes converge almost surely to the deterministic approximations. This result leverages large random matrix theory tools and establishes strong convergence guarantees.

Contribution

Asymptotic analysis revealing BBP-like phase transition with signed result

The authors investigate the large-time limit of the learning dynamics and show a phase transition analogous to the BBP phenomenon. Unlike the unsigned BBP result concerning squared inner products, they derive a signed result that depends on initial conditions and the signal-to-noise ratio.

Gradient Descent Dynamics of Rank-One Matrix Denoising | Novelty Validation