Hard Legendrian unknots

Fuente: arXiv
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Main Authors: Breen, Joseph, Christian, Austin, Wu, Angela
Format: Preprint
Published: 2026
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author Breen, Joseph
Christian, Austin
Wu, Angela
author_facet Breen, Joseph
Christian, Austin
Wu, Angela
contents We initiate the study of Reidemeister hardness of Legendrian unknot front projections. Using normal rulings, we obstruct several infinite families of hard unknot diagrams from being drawn with max-tb unknot fronts, along with 1.7 million of the 2.6 million hard unknot diagrams studied in \cite{applebaum2024unknottingnumberhardunknot}. We construct infinitely many smoothly hard max-tb unknot diagrams, and bound their minimum possible writhe. With respect to these bounds, our constructions are conjecturally sharp.
format Preprint
id arxiv_https___arxiv_org_abs_2604_27213
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Hard Legendrian unknots
Breen, Joseph
Christian, Austin
Wu, Angela
Geometric Topology
Symplectic Geometry
57K33 (Primary) 57K10 (Secondary)
We initiate the study of Reidemeister hardness of Legendrian unknot front projections. Using normal rulings, we obstruct several infinite families of hard unknot diagrams from being drawn with max-tb unknot fronts, along with 1.7 million of the 2.6 million hard unknot diagrams studied in \cite{applebaum2024unknottingnumberhardunknot}. We construct infinitely many smoothly hard max-tb unknot diagrams, and bound their minimum possible writhe. With respect to these bounds, our constructions are conjecturally sharp.
title Hard Legendrian unknots
topic Geometric Topology
Symplectic Geometry
57K33 (Primary) 57K10 (Secondary)
url https://arxiv.org/abs/2604.27213