On the Diameter of a 2-Sum of Polyhedra

Fuente: arXiv
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Autori principali: Borgwardt, Steffen, Grewe, Weston, Lee, Jon
Natura: Preprint
Pubblicazione: 2023
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author Borgwardt, Steffen
Grewe, Weston
Lee, Jon
author_facet Borgwardt, Steffen
Grewe, Weston
Lee, Jon
contents The study of the combinatorial diameter of a polyhedron is a classical topic in linear-programming theory due to its close connection with the possibility of a polynomial simplex-method pivot rule. The 2-sum operation is a classical operation for graphs, matrices, and matroids; we extend this definition to polyhedra. We analyze the diameters of 2-sum polyhedra, which are those polyhedra that arise from this operation. These polyhedra appear in matroid and integer-programming theory as a natural way to link two systems in a joint model with a single shared constraint and the 2-sum also appears as a key operation in Seymour's decomposition theorem for totally-unimodular matrices. We show that the diameter of a 2-sum polyhedron is quadratic in the diameters of its summands. The methods transfer to a linear bound for the addition of a unit column to an equality system, or equivalently, to the relaxation of an equality constraint to an inequality constraint. Further, we use our methods to analyze the distance between vertices on certain faces of a 3-sum polyhedron.
format Preprint
id arxiv_https___arxiv_org_abs_2311_02047
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle On the Diameter of a 2-Sum of Polyhedra
Borgwardt, Steffen
Grewe, Weston
Lee, Jon
Optimization and Control
52B05, 52B40, 90C05
The study of the combinatorial diameter of a polyhedron is a classical topic in linear-programming theory due to its close connection with the possibility of a polynomial simplex-method pivot rule. The 2-sum operation is a classical operation for graphs, matrices, and matroids; we extend this definition to polyhedra. We analyze the diameters of 2-sum polyhedra, which are those polyhedra that arise from this operation. These polyhedra appear in matroid and integer-programming theory as a natural way to link two systems in a joint model with a single shared constraint and the 2-sum also appears as a key operation in Seymour's decomposition theorem for totally-unimodular matrices. We show that the diameter of a 2-sum polyhedron is quadratic in the diameters of its summands. The methods transfer to a linear bound for the addition of a unit column to an equality system, or equivalently, to the relaxation of an equality constraint to an inequality constraint. Further, we use our methods to analyze the distance between vertices on certain faces of a 3-sum polyhedron.
title On the Diameter of a 2-Sum of Polyhedra
topic Optimization and Control
52B05, 52B40, 90C05
url https://arxiv.org/abs/2311.02047