On The Cost Function Associated With Legendrian Knots

Fuente: arXiv
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Autores principales: Kulkarni, Dheeraj, Shah, Tanushree, Yadav, Monika
Formato: Preprint
Publicado: 2023
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author Kulkarni, Dheeraj
Shah, Tanushree
Yadav, Monika
author_facet Kulkarni, Dheeraj
Shah, Tanushree
Yadav, Monika
contents In this article, we introduce a non-negative integer-valued function that measures the obstruction for converting topological isotopy between two Legendrian knots into a Legendrian isotopy. We refer to this function as the Cost function. We show that the Cost function induces a metric on the set of topologically isotopic Legendrian knots. Hence, the set of topologically isotopic Legendrian knots can be seen as a graph with path-metric given by the Cost function. Legendrian simple knot types are shown to be characterized using the Cost function. We also get a quantitative version of Fuchs-Tabachnikov's Theorem that says any two Legendrian knots in $(\mathbb{S}^3,ξ_{std})$ in the same topological knot type become Legendrian isotopic after sufficiently many stabilizations. We compute the Cost function for Legendrian simple knots (for example torus knots) and we note the behavior of Cost function for twist knots and cables of torus knots (some of which are Legendrian non-simple). We also construct examples of Legendrian representatives of 2-bridge knots and compute the Cost between them. Further, we investigate the behavior of the Cost function under the connect sum operation. We conclude with some questions about the Cost function, its relation with the standard contact structure, and the topological knot type.
format Preprint
id arxiv_https___arxiv_org_abs_2307_13963
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle On The Cost Function Associated With Legendrian Knots
Kulkarni, Dheeraj
Shah, Tanushree
Yadav, Monika
Geometric Topology
Symplectic Geometry
57K10, 57K14, 57K33
In this article, we introduce a non-negative integer-valued function that measures the obstruction for converting topological isotopy between two Legendrian knots into a Legendrian isotopy. We refer to this function as the Cost function. We show that the Cost function induces a metric on the set of topologically isotopic Legendrian knots. Hence, the set of topologically isotopic Legendrian knots can be seen as a graph with path-metric given by the Cost function. Legendrian simple knot types are shown to be characterized using the Cost function. We also get a quantitative version of Fuchs-Tabachnikov's Theorem that says any two Legendrian knots in $(\mathbb{S}^3,ξ_{std})$ in the same topological knot type become Legendrian isotopic after sufficiently many stabilizations. We compute the Cost function for Legendrian simple knots (for example torus knots) and we note the behavior of Cost function for twist knots and cables of torus knots (some of which are Legendrian non-simple). We also construct examples of Legendrian representatives of 2-bridge knots and compute the Cost between them. Further, we investigate the behavior of the Cost function under the connect sum operation. We conclude with some questions about the Cost function, its relation with the standard contact structure, and the topological knot type.
title On The Cost Function Associated With Legendrian Knots
topic Geometric Topology
Symplectic Geometry
57K10, 57K14, 57K33
url https://arxiv.org/abs/2307.13963