Irreducible components of sets of points in the plane that satisfy distance conditions

Fuente: arXiv
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Autores principales: Lubbes, Niels, Makhul, Mehdi, Schicho, Josef, Warren, Audie
Formato: Preprint
Publicado: 2024
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author Lubbes, Niels
Makhul, Mehdi
Schicho, Josef
Warren, Audie
author_facet Lubbes, Niels
Makhul, Mehdi
Schicho, Josef
Warren, Audie
contents For a given graph whose edges are labeled with general real numbers, we consider the set of functions from the vertex set into the Euclidean plane such that the distance between the images of neighbouring vertices is equal to the corresponding edge label. This set of functions can be expressed as the zero set of quadratic polynomials and our main result characterizes the number of complex irreducible components of this zero set in terms of combinatorial properties of the graph. In case the complex components are three-dimensional, then the graph is minimally rigid and the component number is a well-known invariant from rigidity theory. If the components are four-dimensional, then they correspond to one-dimensional coupler curves of flexible planar mechanisms. As an application, we characterize the degree of irreducible components of such coupler curves combinatorially.
format Preprint
id arxiv_https___arxiv_org_abs_2403_00392
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Irreducible components of sets of points in the plane that satisfy distance conditions
Lubbes, Niels
Makhul, Mehdi
Schicho, Josef
Warren, Audie
Combinatorics
Algebraic Geometry
Metric Geometry
52C25, 70B15, 51K05, 51F99
For a given graph whose edges are labeled with general real numbers, we consider the set of functions from the vertex set into the Euclidean plane such that the distance between the images of neighbouring vertices is equal to the corresponding edge label. This set of functions can be expressed as the zero set of quadratic polynomials and our main result characterizes the number of complex irreducible components of this zero set in terms of combinatorial properties of the graph. In case the complex components are three-dimensional, then the graph is minimally rigid and the component number is a well-known invariant from rigidity theory. If the components are four-dimensional, then they correspond to one-dimensional coupler curves of flexible planar mechanisms. As an application, we characterize the degree of irreducible components of such coupler curves combinatorially.
title Irreducible components of sets of points in the plane that satisfy distance conditions
topic Combinatorics
Algebraic Geometry
Metric Geometry
52C25, 70B15, 51K05, 51F99
url https://arxiv.org/abs/2403.00392