A-polynomials, Ptolemy equations and Dehn filling

Fuente: arXiv
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Hauptverfasser: Howie, Joshua A., Mathews, Daniel V., Purcell, Jessica S.
Format: Preprint
Veröffentlicht: 2020
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author Howie, Joshua A.
Mathews, Daniel V.
Purcell, Jessica S.
author_facet Howie, Joshua A.
Mathews, Daniel V.
Purcell, Jessica S.
contents The A-polynomial encodes hyperbolic geometric information on knots and related manifolds. Historically, it has been difficult to compute, and particularly difficult to determine A-polynomials of infinite families of knots. Here, we compute A-polynomials by starting with a triangulation of a manifold, then using symplectic properties of the Neumann-Zagier matrix encoding the gluings to change the basis of the computation. The result is a simplification of the defining equations. We apply this method to families of manifolds obtained by Dehn filling, and show that the defining equations of their A-polynomials are Ptolemy equations which, up to signs, are equations between cluster variables in the cluster algebra of the cusp torus.
format Preprint
id arxiv_https___arxiv_org_abs_2002_10356
institution arXiv
publishDate 2020
record_format arxiv
spellingShingle A-polynomials, Ptolemy equations and Dehn filling
Howie, Joshua A.
Mathews, Daniel V.
Purcell, Jessica S.
Geometric Topology
Symplectic Geometry
57K31, 57K32, 57K14
The A-polynomial encodes hyperbolic geometric information on knots and related manifolds. Historically, it has been difficult to compute, and particularly difficult to determine A-polynomials of infinite families of knots. Here, we compute A-polynomials by starting with a triangulation of a manifold, then using symplectic properties of the Neumann-Zagier matrix encoding the gluings to change the basis of the computation. The result is a simplification of the defining equations. We apply this method to families of manifolds obtained by Dehn filling, and show that the defining equations of their A-polynomials are Ptolemy equations which, up to signs, are equations between cluster variables in the cluster algebra of the cusp torus.
title A-polynomials, Ptolemy equations and Dehn filling
topic Geometric Topology
Symplectic Geometry
57K31, 57K32, 57K14
url https://arxiv.org/abs/2002.10356