The rectangle condition does not detect the strong irreducibility

Fuente: arXiv
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Main Authors: Kwon, Bo-hyun, Kang, Sungmo, Lee, Jung Hoon
Format: Preprint
Published: 2025
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author Kwon, Bo-hyun
Kang, Sungmo
Lee, Jung Hoon
author_facet Kwon, Bo-hyun
Kang, Sungmo
Lee, Jung Hoon
contents The rectangle condition for a genus $g$ Heegaard splitting of a 3-manifold, defined by Casson and Gordon, provides a sufficient criterion for the Heegaard splitting to be strongly irreducible. However it is unknown whether there exists a strongly irreducible Heegaard splitting which does not satisfy the rectangle condition. In this paper we provide a counterexample of a genus 2 Heegaard splitting of a 3-manifold which is strongly irreducible but fails to satisfy the rectangle condition. The way of constructing such an example is to take a double branched cover of a 3-bridge decomposition of a knot in $S^3$ which is strongly irreducible but does not meet the rectangle condition. This implies that the rectangle condition does not detect the strong irreducibility. As our next goal, we expect that this result provides the weaker version of the rectangle condition which detects the strong irreducibility.
format Preprint
id arxiv_https___arxiv_org_abs_2509_11701
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle The rectangle condition does not detect the strong irreducibility
Kwon, Bo-hyun
Kang, Sungmo
Lee, Jung Hoon
Geometric Topology
Primary 57K10
The rectangle condition for a genus $g$ Heegaard splitting of a 3-manifold, defined by Casson and Gordon, provides a sufficient criterion for the Heegaard splitting to be strongly irreducible. However it is unknown whether there exists a strongly irreducible Heegaard splitting which does not satisfy the rectangle condition. In this paper we provide a counterexample of a genus 2 Heegaard splitting of a 3-manifold which is strongly irreducible but fails to satisfy the rectangle condition. The way of constructing such an example is to take a double branched cover of a 3-bridge decomposition of a knot in $S^3$ which is strongly irreducible but does not meet the rectangle condition. This implies that the rectangle condition does not detect the strong irreducibility. As our next goal, we expect that this result provides the weaker version of the rectangle condition which detects the strong irreducibility.
title The rectangle condition does not detect the strong irreducibility
topic Geometric Topology
Primary 57K10
url https://arxiv.org/abs/2509.11701