Improved Approximation Algorithms for Orthogonally Constrained Problems Using Semidefinite Optimization

Fuente: arXiv
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Main Authors: Cory-Wright, Ryan, Pauphilet, Jean
Format: Preprint
Published: 2025
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author Cory-Wright, Ryan
Pauphilet, Jean
author_facet Cory-Wright, Ryan
Pauphilet, Jean
contents Building on the blueprint from Goemans and Williamson (1995) for the Max-Cut problem, we construct a polynomial-time approximation algorithm for orthogonally constrained quadratic optimization problems. First, we derive a semidefinite relaxation and propose a randomized rounding algorithm to generate feasible solutions from the relaxation. Second, we derive constant-factor approximation guarantees for our algorithm. When optimizing for $m$ orthonormal vectors in dimension $n$, we leverage strong duality and semidefinite complementary slackness to show that our algorithm achieves a $1/3$-approximation ratio. For any $m$ of the form $2^q$ for some integer $q$, we also construct an instance where the performance of our algorithm is exactly $(m+2)/(3m)$, which can be made arbitrarily close to $1/3$ by taking $m \rightarrow + \infty$, hence showing that our analysis is tight.
format Preprint
id arxiv_https___arxiv_org_abs_2501_02942
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Improved Approximation Algorithms for Orthogonally Constrained Problems Using Semidefinite Optimization
Cory-Wright, Ryan
Pauphilet, Jean
Optimization and Control
Machine Learning
Probability
Building on the blueprint from Goemans and Williamson (1995) for the Max-Cut problem, we construct a polynomial-time approximation algorithm for orthogonally constrained quadratic optimization problems. First, we derive a semidefinite relaxation and propose a randomized rounding algorithm to generate feasible solutions from the relaxation. Second, we derive constant-factor approximation guarantees for our algorithm. When optimizing for $m$ orthonormal vectors in dimension $n$, we leverage strong duality and semidefinite complementary slackness to show that our algorithm achieves a $1/3$-approximation ratio. For any $m$ of the form $2^q$ for some integer $q$, we also construct an instance where the performance of our algorithm is exactly $(m+2)/(3m)$, which can be made arbitrarily close to $1/3$ by taking $m \rightarrow + \infty$, hence showing that our analysis is tight.
title Improved Approximation Algorithms for Orthogonally Constrained Problems Using Semidefinite Optimization
topic Optimization and Control
Machine Learning
Probability
url https://arxiv.org/abs/2501.02942