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Detecting Heegaard Floer homology solid tori

Akram Alishahi, Tye Lidman, Robert Lipshitz

TL;DR

The paper establishes a sharp geometric criterion for Heegaard Floer homology solid tori (HFSTs): a rational homology solid torus $M$ is an HFST iff the Dehn filling along its rational longitude, $M(\lambda)$, contains a non-separating $S^2$. It leverages both the classical bordered Floer framework and the immersed-curve reformulation to relate HFSTs to twisted surgery data and to show that all HFSTs arise as knot complements in reducible manifolds. It then classifies Seifert-fibered HFSTs, showing they occur precisely when the base orbifold is a Möbius band or when the filled space is $D^2(0;p/q,-p/q)$. The results connect bordered Floer theory, twisted coefficients, and immersed-curve techniques to provide a complete picture of HFSTs and their Seifert-fibered instances, with implications for L-space fillings and non-separating sphere phenomena.

Abstract

We show that a rational homology solid torus is a Heegaard Floer homology solid torus if and only if it has a Dehn filling with a non-separating 2-sphere. Using this, we characterize Seifert fibered Heegaard Floer solid tori.

Detecting Heegaard Floer homology solid tori

TL;DR

The paper establishes a sharp geometric criterion for Heegaard Floer homology solid tori (HFSTs): a rational homology solid torus is an HFST iff the Dehn filling along its rational longitude, , contains a non-separating . It leverages both the classical bordered Floer framework and the immersed-curve reformulation to relate HFSTs to twisted surgery data and to show that all HFSTs arise as knot complements in reducible manifolds. It then classifies Seifert-fibered HFSTs, showing they occur precisely when the base orbifold is a Möbius band or when the filled space is . The results connect bordered Floer theory, twisted coefficients, and immersed-curve techniques to provide a complete picture of HFSTs and their Seifert-fibered instances, with implications for L-space fillings and non-separating sphere phenomena.

Abstract

We show that a rational homology solid torus is a Heegaard Floer homology solid torus if and only if it has a Dehn filling with a non-separating 2-sphere. Using this, we characterize Seifert fibered Heegaard Floer solid tori.
Paper Structure (7 sections, 7 theorems, 7 equations, 2 figures)

This paper contains 7 sections, 7 theorems, 7 equations, 2 figures.

Key Result

Theorem 1.1

Let $M$ be a rational homology solid torus and let $\lambda$ denote the rational longitude. Then $M$ is a Heegaard Floer homology solid torus if and only if $M(\lambda)$ contains a non-separating 2-sphere.

Figures (2)

  • Figure 1: An example of the first case in the proof of Proposition \ref{['prop:other-easy-dir']}. The longitude is dashed and the immersed curve is solid; this pair is admissible.
  • Figure 2: An example of the second case in the proof of Proposition \ref{['prop:other-easy-dir']}. Left: the immersed curve invariant, with conventions as in Figure \ref{['fig:admissible-case']}. This pair is not admissible. Center: the corresponding bordered invariant. Right: the tensor product with $\underline{\mathcal{S}}$.

Theorems & Definitions (14)

  • Theorem 1.1
  • Proposition 1.2
  • Theorem 1.3
  • Remark 1.4
  • Lemma 2.1
  • proof
  • Lemma 2.2
  • proof
  • Proposition 3.1
  • proof
  • ...and 4 more