Provable Exactness for Asymmetric Low-Rank SDP Learning

Fuente: arXiv
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Main Author: Hu, Enliang
Format: Preprint
Published: 2018
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author Hu, Enliang
author_facet Hu, Enliang
contents Low-rank factorization is a standard way to make structured optimization problems in machine learning more tractable by replacing matrix variables with compact factors. For positive semidefinite (PSD) variables, the symmetric Burer--Monteiro factorization (sBMF) writes $Z=XX^\top$ with a single low-rank factor $X$. A recent asymmetric alternative (aBMF) writes $Z=XY^\top$ and adds a quadratic penalty $(γ/2)\|X-Y\|_F^2$ to encourage symmetry. This split is attractive because it yields a biconvex objective with alternating convex subproblems, but its practical value depends strongly on how the penalty parameter $γ$ is chosen. We study a unified regularized aBMF framework and derive an explicit lower bound on $γ$ that guarantees exactness: under mild assumptions, any $γ$ above this threshold makes aBMF and sBMF share the same critical points. This gives a principled way to use the asymmetric formulation without altering the critical-point structure of the symmetric problem. In particular, it answers the open question of whether an exact penalty exists for asymmetric relaxation.
format Preprint
id arxiv_https___arxiv_org_abs_1811_01198
institution arXiv
publishDate 2018
record_format arxiv
spellingShingle Provable Exactness for Asymmetric Low-Rank SDP Learning
Hu, Enliang
Machine Learning
Optimization and Control
Low-rank factorization is a standard way to make structured optimization problems in machine learning more tractable by replacing matrix variables with compact factors. For positive semidefinite (PSD) variables, the symmetric Burer--Monteiro factorization (sBMF) writes $Z=XX^\top$ with a single low-rank factor $X$. A recent asymmetric alternative (aBMF) writes $Z=XY^\top$ and adds a quadratic penalty $(γ/2)\|X-Y\|_F^2$ to encourage symmetry. This split is attractive because it yields a biconvex objective with alternating convex subproblems, but its practical value depends strongly on how the penalty parameter $γ$ is chosen. We study a unified regularized aBMF framework and derive an explicit lower bound on $γ$ that guarantees exactness: under mild assumptions, any $γ$ above this threshold makes aBMF and sBMF share the same critical points. This gives a principled way to use the asymmetric formulation without altering the critical-point structure of the symmetric problem. In particular, it answers the open question of whether an exact penalty exists for asymmetric relaxation.
title Provable Exactness for Asymmetric Low-Rank SDP Learning
topic Machine Learning
Optimization and Control
url https://arxiv.org/abs/1811.01198