Optimization over bounded-rank matrices through a desingularization enables joint global and local guarantees

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Hauptverfasser: Rebjock, Quentin, Boumal, Nicolas
Format: Preprint
Veröffentlicht: 2024
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author Rebjock, Quentin
Boumal, Nicolas
author_facet Rebjock, Quentin
Boumal, Nicolas
contents Convergence guarantees for optimization over bounded-rank matrices are delicate to obtain because the feasible set is a non-smooth and non-convex algebraic variety. Existing techniques include projected gradient descent, fixed-rank optimization (over the maximal-rank stratum), and the LR parameterization. They all lack either global guarantees (the ability to accumulate only at critical points) or fast local convergence (e.g., if the limit has non-maximal rank). We seek optimization algorithms that enjoy both. Khrulkov and Oseledets [2018] parameterize the bounded-rank variety via a desingularization to recast the optimization problem onto a smooth manifold. Building on their ideas, we develop a Riemannian geometry for this desingularization, also with care for numerical considerations. We use it to secure global convergence to critical points with fast local rates, for a large range of algorithms. On matrix completion tasks, we find that this approach is comparable to others, while enjoying better general-purpose theoretical guarantees.
format Preprint
id arxiv_https___arxiv_org_abs_2406_14211
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Optimization over bounded-rank matrices through a desingularization enables joint global and local guarantees
Rebjock, Quentin
Boumal, Nicolas
Optimization and Control
Numerical Analysis
Convergence guarantees for optimization over bounded-rank matrices are delicate to obtain because the feasible set is a non-smooth and non-convex algebraic variety. Existing techniques include projected gradient descent, fixed-rank optimization (over the maximal-rank stratum), and the LR parameterization. They all lack either global guarantees (the ability to accumulate only at critical points) or fast local convergence (e.g., if the limit has non-maximal rank). We seek optimization algorithms that enjoy both. Khrulkov and Oseledets [2018] parameterize the bounded-rank variety via a desingularization to recast the optimization problem onto a smooth manifold. Building on their ideas, we develop a Riemannian geometry for this desingularization, also with care for numerical considerations. We use it to secure global convergence to critical points with fast local rates, for a large range of algorithms. On matrix completion tasks, we find that this approach is comparable to others, while enjoying better general-purpose theoretical guarantees.
title Optimization over bounded-rank matrices through a desingularization enables joint global and local guarantees
topic Optimization and Control
Numerical Analysis
url https://arxiv.org/abs/2406.14211