Hopf Arborescent Links, Minor Theory, and Decidability of the Genus Defect

Fuente: arXiv
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Main Authors: Dehornoy, Pierre, Lunel, Corentin, de Mesmay, Arnaud
Format: Preprint
Published: 2023
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author Dehornoy, Pierre
Lunel, Corentin
de Mesmay, Arnaud
author_facet Dehornoy, Pierre
Lunel, Corentin
de Mesmay, Arnaud
contents While the problem of computing the genus of a knot is now fairly well understood, no algorithm is known for its four-dimensional variants, both in the smooth and in the topological locally flat category. In this article, we investigate a class of knots and links called Hopf arborescent links, which are obtained as the boundaries of some iterated plumbings of Hopf bands. We show that for such links, computing the genus defects, which measure how much the four-dimensional genera differ from the classical genus, is decidable. Our proof is non-constructive, and is obtained by proving that Seifert surfaces of Hopf arborescent links under a relation of minors defined by containment of their Seifert surfaces form a well-quasi-order.
format Preprint
id arxiv_https___arxiv_org_abs_2312_09094
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Hopf Arborescent Links, Minor Theory, and Decidability of the Genus Defect
Dehornoy, Pierre
Lunel, Corentin
de Mesmay, Arnaud
Computational Geometry
Geometric Topology
While the problem of computing the genus of a knot is now fairly well understood, no algorithm is known for its four-dimensional variants, both in the smooth and in the topological locally flat category. In this article, we investigate a class of knots and links called Hopf arborescent links, which are obtained as the boundaries of some iterated plumbings of Hopf bands. We show that for such links, computing the genus defects, which measure how much the four-dimensional genera differ from the classical genus, is decidable. Our proof is non-constructive, and is obtained by proving that Seifert surfaces of Hopf arborescent links under a relation of minors defined by containment of their Seifert surfaces form a well-quasi-order.
title Hopf Arborescent Links, Minor Theory, and Decidability of the Genus Defect
topic Computational Geometry
Geometric Topology
url https://arxiv.org/abs/2312.09094