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Auteurs principaux: Blanco, Víctor, Laborda, Diego, Martínez-Antón, Miguel
Format: Preprint
Publié: 2025
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Accès en ligne:https://arxiv.org/abs/2510.09166
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author Blanco, Víctor
Laborda, Diego
Martínez-Antón, Miguel
author_facet Blanco, Víctor
Laborda, Diego
Martínez-Antón, Miguel
contents We study the conditions under which the convex relaxation of a mixed-integer linear programming formulation for ordered optimization problems, where sorting is part of the decision process, yields integral optimal solutions. Thereby solving the problem exactly in polynomial time. Our analysis identifies structural properties of the input data that influence the integrality of the relaxation. We show that incorporating ordered components introduces additional layers of combinatorial complexity that invalidate the exactness observed in classical (non-ordered) settings. In particular, for certain ordered problems such as the min--max case, the linear relaxation never recovers the integral solution. These results clarify the intrinsic hardness introduced by sorting and reveal that the strength of the relaxation depends critically on the ``proximity'' of the ordered problem to its classical counterpart: problems closer to the non-ordered case tend to admit tighter relaxations, while those further away exhibit substantially weaker behavior. Computational experiments on benchmark instances confirm the predictive value of the integrality conditions and demonstrate the practical implications of exact relaxations for ordered location problems.
format Preprint
id arxiv_https___arxiv_org_abs_2510_09166
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle On the Strength of Linear Relaxations in Ordered Optimization
Blanco, Víctor
Laborda, Diego
Martínez-Antón, Miguel
Optimization and Control
We study the conditions under which the convex relaxation of a mixed-integer linear programming formulation for ordered optimization problems, where sorting is part of the decision process, yields integral optimal solutions. Thereby solving the problem exactly in polynomial time. Our analysis identifies structural properties of the input data that influence the integrality of the relaxation. We show that incorporating ordered components introduces additional layers of combinatorial complexity that invalidate the exactness observed in classical (non-ordered) settings. In particular, for certain ordered problems such as the min--max case, the linear relaxation never recovers the integral solution. These results clarify the intrinsic hardness introduced by sorting and reveal that the strength of the relaxation depends critically on the ``proximity'' of the ordered problem to its classical counterpart: problems closer to the non-ordered case tend to admit tighter relaxations, while those further away exhibit substantially weaker behavior. Computational experiments on benchmark instances confirm the predictive value of the integrality conditions and demonstrate the practical implications of exact relaxations for ordered location problems.
title On the Strength of Linear Relaxations in Ordered Optimization
topic Optimization and Control
url https://arxiv.org/abs/2510.09166